Insulin dosing

ACRONYMS AND DEFINITIONS

ADA - American Diabetes Association

Basal insulin - Long- and intermediate-acting insulins used to supply constant levels of insulin activity over the course of a day

Carb - Carbohydrate

T1DM - Type 1 diabetes

T2DM - Type 2 diabetes

Multidose insulin regimen - Insulin regimens that include both basal and premeal insulins

Prandial insulin - Rapid and short-acting insulins given at mealtime

Premeal insulin - also called “prandial” insulin. Rapid and short-acting insulins given at mealtime.

Total daily dose of insulin - Sum in units of premeal and basal insulin given in a day

1 kilogram = 2.2 pounds

IMPORTANT POINTS ABOUT DOSING INSULIN

Overview

There are a number of different ways to dose insulin, and no single regimen will work for every patient. Patient variables like education, motivation, diabetes control, and resources must all be considered when determining which method will best fit each individual.

Low blood sugar (Hypoglycemia)

In most patients, the main concern when initiating insulin is the risk of low blood sugars. To help lower the risk, blood sugar monitoring should be increased, and all patients should be aware of the signs, symptoms, and treatment of hypoglycemia (see hypoglycemia for more).

Measures to help prevent low blood sugars

Insulin-naïve patients should start at the lower end of dosing ranges and titrate slowly
Patients should try to avoid insulin doses outside of their prescribed regimens as this may lead to incorrect adjustments
Patients should attempt to consume a consistent diet of three meals a day while also keeping meals as uniform as possible in size and carbohydrate content. Patients should notify their provider and increase monitoring if they decide to make significant changes to their diet (e.g. start a keto diet, drastically reduce calorie intake).
When using a multidose regimen (basal and premeal), adjust one regimen at a time and alternate between the two (see alternating regimens for more)

INSULIN CATEGORIES

For dosing purposes, insulins can be divided into two categories:

Basal insulins - basal insulins provide a steady amount of background insulin activity over the course of a day
Premeal insulin (prandial insulin) - premeal insulins provide a burst of insulin that acts quickly to abate the rise in blood glucose that is seen after consuming a meal
See insulin chart for a review of available insulins including their pharmacokinetics, dosage forms, storage, and more

Basal insulins

Intermediate-acting insulins

Humulin® N (NPH)
Novolin® N (NPH)

Long-acting insulins

Basaglar® (insulin glargine)
Lantus® (insulin glargine)
Levemir® (insulin detemir)
Semglee® (insulin glargine)
Toujeo® (insulin glargine)
Tresiba® (insulin degludec)

Premeal insulins

Rapid-acting insulins

Admelog® (insulin lispro)
Afrezza® (inhaled insulin)
Apidra® (insulin glulisine)
Fiasp® (insulin aspart)
Humalog® (insulin lispro)
Lyumjev® (insulin lispro-aabc)
Novolog® (insulin aspart)

Short-acting insulins

Humulin® R (regular)
Novolin® R (regular)

BLOOD SUGAR GOALS

See ADA blood sugar goals in DM

TYPE 1 DIABETES INSULIN RECOMMENDATIONS

ADA general treatment recommendations for T1DM

T1DM patients should receive multidose injections (3 - 4 a day) of basal and premeal insulin or insulin pump therapy
Most individuals with T1DM should use rapid-acting insulin analogs to reduce hypoglycemia risk
Patients should match premeal insulin to carbohydrate intake, premeal blood glucose levels, and anticipated activity [26]

Starting therapy

Insulin dosing in T1DM will vary based on patient's age, weight, and residual pancreatic insulin activity
T1DM patients will typically require a total daily insulin dose of 0.4 - 1.0 units/kg/day
A typical starting dose in metabolically-stable patients is 0.5 units/kg/day
After calculating the total daily dose, it should be given as follows:

Basal insulin - given as half of the total daily dose ^✝
Premeal insulin - half of the total daily dose divided into thirds and given before each meal

^✝ When first starting therapy, it is recommended that the initial basal dose be reduced by 20 - 30% to prevent hypoglycemia [11,19]

T1DM patients may experience a "honeymoon phase" after starting insulin therapy where the initial effects of insulin are greater than what is seen later in the disease [7,13,26]

Example

Patient weighs 80 kg
Total daily dose = 80 kg X (0.5 units/kg/d) = 40 units per day
Basal insulin = 1/2 X 40 units = 20 units of basal per day^✝
Premeal Insulin = 1/2 X 40 units = 20 units / 3 = approximately 7 units before each meal

^✝ If patient is just starting therapy, the initial basal dose should be reduced by 20 - 30%. In our example: 20 units X 0.20 = 4 units, so initial basal dose would be 20 - 4 = 16 units

Adjusting therapy

See adjusting basal insulin and adjusting premeal insulin below

TYPE 2 DIABETES INSULIN RECOMMENDATIONS

Reference [27]
ADA Insulin Dosing Recommendations for Adults with T2DM
Step 1 - start with long-acting insulin or bedtime NPH Initial dose: 10 units/day or 0.1 - 0.2 units/kg/day Adjust dose: increase dose by 10 - 15% or 2 - 4 units once or twice weekly to achieve fasting blood sugar goal (see adjusting basal insulin and NPH dosing for more) If hypoglycemia occurs: decrease dose by 10 - 20% or 4 units If A1C is still above target despite achieving fasting blood sugar goal, or if A1C is not at target and insulin dose is > 0.7 - 1.0 units/kg, proceed to Step 2
Step 2 - add premeal insulin before largest meal Initial dose: 4 units or 10% of basal dose If A1C < 8%, consider decreasing basal insulin dose by same amount Adjust dose: increase dose by 1 - 2 units or 10 - 15% twice weekly to achieve pre- and postprandial goals (see adjusting premeal insulin for more) If hypoglycemia occurs: decrease dose 2 - 4 units or 10 - 20% For patients using bedtime NPH: Consider switching to twice daily NPH by taking 80% of current bedtime NPH dose and giving 2/3 in the morning and 1/3 at bedtime. See NPH dosing for more. Example: Current bedtime NPH dose is 30 units 0.80 X 30 = 24 units 2/3 of 24 = 16 units in the morning 1/3 of 24 = 8 units in the evening If A1C still not at target, proceed to Step 3
Step 3 - add premeal insulin before other meals in stepwise fashion Add prandial insulin to an additional meal and use the guidelines in Step 2 to adjust If not controlled with 2 preprandial doses, add to a third meal Stepwise addition of prandial insulin every 3 months is associated with a lower risk of hypoglycemia and greater patient satisfaction

Reference [27]
ADA Insulin Recommendations for Youth with T2DM
Basal insulin Initial dose: 0.5 units/kg/day Adjust dose: Increase every 3 - 5 days based on blood sugar readings to a maximum of 1.5 units/kg/day (see adjusting basal insulin for more) If pancreatic autoantibodies are positive, consider starting basal-premeal regimen or insulin pump therapy

Reference [27]
ADA Insulin Recommendations for Elderly with T2DM
Overview In order to avoid hypoglycemia, the ADA recommends that insulin regimens be simplified in elderly patients who have cognitive impairment, multiple coexisting chronic illnesses, and/or functional dependence The information below gives general recommendations that can be used for simplifying regimens in appropriate patients
Basal insulin Change timing from bedtime to morning When titrating basal insulin, use a fasting blood sugar goal of 90 - 150 mg/dl and make adjustments based on a week of values If 50% of fasting blood sugar values are above goal, increase basal dose by 2 units If > 2 fasting blood sugar values/week are < 80 mg/dl, decrease basal dose by 2 units
Premeal (prandial) insulin Initial therapy Do not use short-acting insulin at bedtime If premeal insulin dose is ≤ 10 units, discontinue premeal insulin and add noninsulin agent If premeal insulin dose is > 10 units, decrease dose by 50% and add noninsulin agent. Titrate noninsulin agent while decreasing premeal insulin dose with goal of stopping premeal insulin. Adjusting therapy Use a blood glucose premeal goal of 90 - 150 mg/dl Every 2 weeks, adjust insulin dose and noninsulin therapy based on pre-lunch and pre-dinner glucose readings If 50% of premeal blood sugar values are above goal over 2 weeks, increase intensity of noninsulin therapy If > 2 premeal values/week are < 90 mg/dl, decrease intensity of therapy Sliding scale for premeal blood sugar values Blood sugar > 250 mg/dl: give 2 units of short- or rapid-acting insulin Blood sugar > 350 mg/dl: give 4 units of short- or rapid-acting insulin Noninsulin agents If GFR ≥ 45 ml/min, use metformin as noninsulin agent If GFR < 45 ml/min or metformin is already being used, see T2DM treatment recommendations for guidance on other agents

ADJUSTING BASAL INSULIN

Overview

Basal insulins provide a constant level of background insulin activity. In T2DM, they can be used as monotherapy or as a supplement to other therapies. The ADA recommends that insulin be considered as an initial therapy in type 2 diabetics who have evidence of ongoing catabolism (e.g. weight loss), symptoms of hyperglycemia, or when A1C is > 10% or blood glucose levels > 300 mg/dL.
Basal insulin recommendations from the ADA are given below. Another method (Three-day method) that provides more specific instructions and has been proven effective in clinical trials is also provided.
When NPH is used as the basal insulin, other considerations should be taken into account. See NPH dosing for more.

ADA recommendations for basal insulin therapy in T2DM

Start with a long-acting insulin or bedtime NPH
Initial dose: 10 units/day or 0.1 - 0.2 units/kg/day
Adjust dose: increase dose by 10 - 15% or 2 - 4 units once or twice weekly to achieve fasting blood sugar goal (see blood sugar goals for more)
If hypoglycemia occurs: decrease dose by 10 - 20% or 4 units

Three-day method for adjusting basal insulin

1. Measure fasting blood sugar (no calories for 8 hours) for previous three consecutive days
2. Calculate the average of the three fasting blood sugars
3. Adjust basal insulin dose based on the table below
4. Repeat steps 1-3 until target range (80 - 99) is achieved

Reference [12]
Fasting blood sugar (mg/dl) average over 3 days	Adjustment to basal insulin dose (units of insulin)
≥ 180	add 8 units
160 - 179	add 6 units
140 - 159	add 4 units
120 - 139	add 2 units
100 - 119	add 1 unit
80 - 99	no change
60 - 79	subtract 2 units
< 60	subtract 4 or more units

ADJUSTING PREMEAL INSULIN

Overview

There are a number of ways to adjust premeal insulin. The ADA gives simple guidance that will likely be appropriate for most type 2 diabetics. More complex methods (scale method and carb counting method) are also detailed below. These methods are probably more appropriate for type 1 diabetics and/or patients who are highly motivated.

ADA recommendations for premeal insulin in T2DM

If A1C is still above target despite achieving fasting blood sugar goal on basal insulin, or if A1C is not at target and insulin dose is > 0.7 - 1.0 units/kg, add premeal insulin
Frequency: Start by adding premeal insulin to the largest meal of the day. If adequate control is not achieved, add premeal insulin to a second and third meal if necessary.
Initial dose: 4 units or 10% of basal dose

If A1C < 8%, consider decreasing basal insulin dose by same amount

Adjust dose: increase dose by 1 - 2 units or 10 - 15% twice weekly to achieve pre- and postprandial goals (see blood sugar goals for more)
If hypoglycemia occurs: decrease dose 2 - 4 units or 10 - 20%

ADJUSTING PREMEAL INSULIN (SCALE METHOD)

Scale method

With the scale method, premeal insulin is adjusted based on a scale
Patients should try to consume the same amount of carbohydrates at each meal (a typical amount is about 60 grams a meal and 15 grams for a bedtime snack)
Carbohydrate goals vary by individual (see carbohydrate information below)

Steps:

1. Measure blood sugar fasting (pre-breakfast), pre-lunch, pre-dinner, and pre-bedtime snack for previous three consecutive days
2. Average the pre-lunch, pre-dinner and pre-bedtime values separately
3. Adjust the premeal insulin dose based on the table below
4. Repeat steps 1-3 until target range is achieved
5. A Correction Factor (see below) should also be incorporated when blood sugars are checked

Reference [12]
Premeal blood sugar (mg/dl) average over 3 days	Adjustment to premeal insulin dose
If pre-lunch average is not in desired range, adjust pre-breakfast dose If pre-dinner average is not in desired range, adjust pre-lunch dose If pre-bedtime snack average is not in desired range, adjust pre-dinner dose
≥ 180	add 3 units
160 - 179	add 2 units
140 - 159	add 2 units
120 - 139	add 1 units
100 - 119	maintain dose (desired range)
80 - 99	subtract 1 unit
60 - 79	subtract 2 units
< 60	subtract 4 or more units

ADJUSTING PREMEAL INSULIN (CARBOHYDRATE COUNTING)

Carbohydrate counting

In carbohydrate counting, premeal insulin is adjusted based on the amount of carbohydrates to be consumed in each meal
The carbohydrate counting method is used to determine the amount of carbohydrates in a meal
An insulin to carbohydrate ratio (ex. 1 unit/10g of carb) is used to calculate the premeal insulin dose
A typical starting ratio is 1 unit of premeal insulin for every 10 grams of carbs to be consumed
An individual may have different carbohydrate ratios for breakfast, lunch, and dinner because a person's response to insulin may vary throughout the day

Example:

60 grams of carbs to be consumed for lunch
Patient's ratio is 1 unit of insulin for every 10 grams of carbs
Patient injects 6 units of premeal insulin before eating meal

Steps for adjusting an insulin-to-carb ratio

1. Calculate the number of carbs to be consumed in a meal using carbohydrate counting
2. Dose premeal insulin based on number of carbs in a meal (typical starting point is 1 unit of premeal insulin for every 10 grams of carbs)
3. Measure blood sugar fasting (pre-breakfast), pre-lunch, pre-dinner, and pre-bedtime snack for previous three consecutive days
4. Average the pre-lunch, pre-dinner and pre-bedtime snack blood sugar values separately
5. Adjust the carbohydrate to insulin ratio as instructed in the table below
6. Repeat steps 1-5 until appropriate ratios are determined [3,4]
7. A Correction Factor (see below) should also be incorporated when blood sugars are checked

If pre-lunch average is not in desired range (80 - 120 mg/dl), adjust breakfast ratio
If pre-dinner average is not in desired range (80 - 120 mg/dl), adjust lunch ratio
If pre-bedtime snack average is not in desired range (80 - 120 mg/dl), adjust dinner ratio

If average blood sugar is > 120 mg/dl, adjust ratio by subtracting 2 - 3g of carbohydrate

Example:

Current ratio 1 unit / 10g of carb
Pre-lunch average > 120 mg/dl
Change breakfast ratio to 1 unit / 7g of carb

If average blood sugar is < 80 mg/dl, adjust ratio by adding 2 - 3g of carbohydrate

Example:

Current ratio 1 unit / 10g of carb
Pre-bedtime snack average < 80 mg/dl
Change dinner ratio to 1 unit / 13g of carb

If average blood sugar is 80 - 120 mg/dl, do not adjust ratio

ADJUSTING PREMEAL AND BASAL INSULINS CONCURRENTLY

Overview

When adjusting premeal and basal insulins concurrently, adjustments to one regimen may affect the other regimen. This can lead to overcorrections and hypoglycemia.
Alternating between regimens may help prevent overcorrections

Example:

Day 3 - adjust basal
Day 6 - adjust premeal
Day 9 - adjust basal
Day 12 - adjust premeal, and so on...

CORRECTION FACTOR

Overview

When premeal blood sugar checks are high, a correction factor should be used with premeal insulin
The correction factor supplies supplemental insulin to account for the elevated blood sugar
Insulin used in the correction factor should not be included in calculations for adjusting premeal or basal insulin
There are several methods that can be used to determine the correction factor
When first starting therapy, the ideal total daily insulin dose will not be known, so the flat method is preferred over the individual method

Flat method
- One unit of extra premeal insulin is added for every 25 mg/dl that blood sugar is above the upper limit of the desired range
- Example:
Individual method

The individual method uses a patient's total daily insulin dose to calculate a correction factor
The correction factor is calculated differently for regular insulins (Humulin R, Novolin R) and rapid insulins (Novolog, Humalog, Apidra, Fiasp)

Step 1 - calculate the correction factor

For Regular insulin (Humulin R, Novolin R)

1. Divide 1500 by the patient's total daily dose of insulin
2. The result will equal the estimated drop in blood sugar (in mg/dl) from 1 unit of regular insulin

For Rapid insulin (Novolog, Humalog, Apidra, Fiasp, Admelog)

1. Divide 1800 by the patient's total daily dose of insulin
2. The result will equal the estimated drop in blood sugar (in mg/dl) from 1 unit of rapid insulin [4,12]

Example:

Patient's total daily dose of insulin (premeal + basal) is 60 units
Patient uses regular insulin as premeal insulin
1500/60 = 25
Patient can expect that for every 1 unit of regular insulin they inject, their blood sugar will come down 25 mg/dl

Step 2 - Once the correction factor is calculated, the patient can then figure out how much insulin to supplement

Example:

Patient from above: correction factor is 25 mg/dl
Patient checks pre-lunch blood sugar and it is 175 mg/dl (desired range 80 - 120 mg/dl)
175 - 120 = 55 mg/dl
55/25 = approximately 2
Patient would add 2 extra units of regular insulin to premeal dose

NPH DOSING

NPH properties

NPH insulin is an intermediate-acting insulin that can be used as a basal insulin. Newer long-acting insulin analogs have largely supplanted NPH insulin as first-line basal insulins, but NPH remains the most affordable insulin available at $25/vial, and it is therefore still an important option for patients without insurance and/or those who are cost sensitive.
When initiating NPH insulin, it's important to understand how its pharmacokinetic properties differ from other basal insulins. Long-acting insulins provide a steady-state of insulin that does not have a peak. NPH insulin has a peak effect that occurs between 4 - 10 hours after dosing. Because of this, NPH carries a higher risk of hypoglycemia. The duration of effect of NPH is around 16 - 20 hours which is shorter than the long-acting insulins that have a duration of 24+ hours. This means NPH often has to be dosed twice daily to achieve sustained control over a 24-hour period.
The diagram below illustrates the different pharmacokinetics of NPH and long-acting insulins. [11,29]

Important points about NPH dosing

NPH is a suspension, and it is important that it is properly resuspended before dosing. Failure to properly resuspend NPH will result in dosing irregularities. Both the vials and the pens contain directions on how to resuspend each product. NPH should appear uniformly white and cloudy after proper resuspension.
Since NPH has a peak effect, it is important that patients keep the timing of their injections and meals consistent in order to help prevent hypoglycemia. Patients should also try to keep their meals uniform in size and carbohydrate content.
Patients who are also using premeal insulins should be aware that NPH may potentiate the peak effect of their premeal insulin. For example, a patient who injects NPH and a rapid-acting insulin before breakfast will see a peak effect from the rapid insulin around 1 - 3 hours after injection. The NPH will start to have its effect around 2 - 3 hours after injection, and the combined peak actions may lead to hypoglycemia. More frequent blood sugar checks and/or dose adjustments may be necessary when initiating therapy.
In the evening, NPH should typically be dosed at bedtime (as opposed to dinner) as this has been shown to decrease the incidence of nighttime hypoglycemia [11,28]

Twice-daily NPH

In type 2 diabetics, twice-daily NPH is appropriate as monotherapy or adjunctive therapy in diabetics who lack significant control (A1C > 9%) despite other treatments. The question that often arises with twice-daily NPH is how much insulin should be given in the morning and how much should be given at night. In studies, NPH regimens have varied widely, with some splitting the dose 50-50, some giving 2/3 in the morning and 1/3 in the evening and others giving 1/3 in the morning and 2/3 in the evening. [30,31,32,33,34,35]
The steps below are derived from clinical trials and guidelines. They are intended to provide a starting point for initiating and adjusting twice-daily NPH in type 2 diabetics. The recommendations should be individualized as some patients may require more aggressive adjustments (e.g. poorly-controlled morbidly obese diabetics) and others may require minor adjustments (e.g. elderly, hypoglycemia concerns). For recommendations in patients who are switching from another insulin to NPH, see converting from other insulins to NPH below.

Dosing NPH Insulin in T2DM

Step 1 - Initial dose

If A1C > 10% and no blood sugars < 126 mg/dl in last 2 weeks ^✝

Start with NPH 10 units twice daily

If A1C < 10% or any blood sugars < 126 mg/dl in last 2 weeks ^✝

Start with NPH 6 units twice daily

Morning dose should be given at approximately the same time each day upon awakening
Evening dose should be given at bedtime

^✝If patient has not been checking blood sugars, have them check and report a fasting blood sugar once they obtain a monitor

Step 2 - Monitor blood sugars

Check fasting blood sugar in the morning and predinner blood sugar in the evening on a daily basis

Step 3 - Determine insulin adjustment

After 3 consecutive days of readings, average all the blood sugars (fasting and predinner) together
Use this average and the table below to determine how much insulin will be added (or subtracted) to the total daily dose

Reference [12]
Blood sugar average (fasting and predinner) over 3 days	Adjustment to total daily NPH dose
≥ 180	add 8 units
160 - 179	add 6 units
140 - 159	add 4 units
120 - 139	add 2 units
100 - 119	add 1 unit
80 - 99	no change
60 - 79	subtract 2 units
< 60	subtract 4 or more units

Step 4 - Distributing the insulin adjustment

Average the fasting and predinner blood sugars over the last 3 days separately
Determine a range for each average (fasting and predinner) from the two tables below

Fasting blood sugar ranges
Average blood sugar (mg/dl)	Range
> 160	3
101 - 160	2
≤ 100	1

Predinner blood sugar ranges
Average blood sugar (mg/dl)	Range
> 160	3
131 - 160	2
≤ 130	1

Use the table below to distribute the additional insulin dose
For fractions of a unit, round up or down. Example: 5.2 units would be 5 units and 2.8 units would be 3 units
If insulin is being subtracted, remove the insulin from the dose or doses that precede the low blood sugar readings
Repeat this process every 3 days until the appropriate blood sugar range is achieved
See the example below for an illustration of how to perform the steps

Fasting range	Predinner range	Dose distribution
1	1	Do not add any NPH insulin
1	2 - 3	Morning - 100% Bedtime - 0%
2	3	Morning - 67% Bedtime - 33%
2	2	Morning - 50% Bedtime - 50%
3	3	Morning - 50% Bedtime - 50%
3	2	Morning - 33% Bedtime - 67%
2 - 3	1	Morning - 0% Bedtime - 100%

Twice-daily NPH example:

Patient initiates NPH insulin at 10 units twice daily
Patient blood sugar readings from 3 consecutive days are as follows:

Fasting: 185, 133, 156
Predinner: 256, 300, 190

Average of all blood sugars = (185 + 133 + 156 + 256 + 300 + 190) / 6 = 203
Based on table in Step 3, patient will add 8 units to the total daily NPH dose
Average of fasting blood sugars is = (185 + 133 + 156)/3 = 158
Average of predinner blood sugars is = (256 + 300 + 190)/3 = 249
Based on tables in Step 4, fasting blood sugars are range 2, and predinner blood sugars are range 3
Based on dose distribution table in Step 4, patient will add 67% of the 8 additional units to his morning dose and 33% to the bedtime dose
67% of 8 = 0.67 X 8 = 5.36 rounded down to 5 units
33% of 8 = 0.33 X 8 = 2.64 rounded up to 3 units
Patient's new NPH dose is 15 units in the morning and 13 units at night

Once-daily NPH

The ADA guidelines list once-daily bedtime NPH as an option when initiating insulin in type 2 diabetics (see ADA T2DM insulin recommendations).
Once-daily NPH is an appropriate adjunctive therapy for type 2 diabetics who have not achieved good control on other therapies. Poorly controlled diabetics (A1C > 9%) will likely need twice-daily NPH to reach their goals. Patients with normal AM fasting blood sugars should give their dose in the morning and not at bedtime.
Dosing recommendations from the ADA are given below. Once-daily NPH can also be adjusted using the three-day method detailed above.

ADA recommendations for bedtime NPH

Initial dose: 10 units/day or 0.1 - 0.2 units/kg/day
Adjust dose: increase dose by 10 - 15% or 2 - 4 units once or twice weekly to achieve fasting blood sugar goal (see blood sugar goals for more)
If hypoglycemia occurs: decrease dose by 10 - 20% or 4 units

Converting from long-acting insulins to NPH

When converting from long-acting insulins to NPH, one of the most important things to consider is that NPH has a peak effect and long-acting insulins do not. The peak effect can increase the risk of hypoglycemia, and this is especially true in patients who are also using premeal insulins. For example, a patient who injects NPH and a rapid-acting insulin before breakfast will see a peak effect from the rapid insulin around 1 - 3 hours after injection. The NPH will start to have its effect around 2 - 3 hours after injection, and the combined peak actions may lead to hypoglycemia.
In trials with type 1 diabetics who were switching from other basal insulins to NPH and vice versa, the total daily basal insulin dose was reduced by 25 - 30% upon initiation. This approach will help prevent hypoglycemia, but may require significant up titration after switching.
Dose changes when switching from long-acting insulins to NPH should be individualized. Patients at greater risk for hypoglycemia should consider a 20 - 30% dose reduction when initiating NPH so they can gauge how the peak effect will affect their blood sugars. This is especially true in patients who are also receiving premeal insulin.
Recommendations from manufacturers for converting between NPH and other insulins are given below - see converting between insulin brands and types [11]

Dosing 70/30 insulin

Novolin 70/30 and Humulin 70/30 contain 70% NPH and 30% regular insulin. Insulin mixes like 70/30 are more difficult to adjust because the premeal and basal insulin must be given at the same time, and they must always be dosed in a 7:3 ratio. Given these constraints, insulin mixes are not widely used any more.
In studies with type 2 diabetics, 70/30 has typically been initiated at doses of 0.2 - 0.6 units/kg/day with two-thirds of the daily dose given before breakfast and one-third given before dinner. The daily dose can then be adjusted up or down in increments of 10% depending on blood sugar readings. [34,35]

SLIDING SCALE INSULIN

Sliding Scale Insulin involves checking the blood sugar and dosing the insulin (typically rapid or short-acting) based on the blood sugar value
Doctors use a number of different regimens depending on the patient and their sensitivity to insulin. The example below is a common starting regimen.

Blood sugar (mg/dl)	Insulin dose in units of rapid or short-acting
< 150	0
150 - 200	2
201 - 250	4
251 - 300	6
301 - 350	8
351 - 400	10
401 - 450	12
> 450	14

CONVERTING BETWEEN INSULIN BRANDS AND TYPES

Overview

Insulin manufacturers make some recommendations when converting between products, but they do not cover every scenario. In addition, there are few trials that have directly compared the glucose-lowering effects of different insulins.
In general, patients who are at high risk for hypoglycemia should reduce the daily dose of their basal insulin by 20 - 30% when switching between insulin products in order to lower the risk of hypoglycemia. All patients should increase blood sugar monitoring when switching insulins to make sure their response to the new product is the same.

Converting between insulin brands and types
Rapid-acting and short-acting insulin When converting between rapid-acting and short-acting insulins, the dose typically remains the same Rapid-acting insulins act quicker (within 10 - 30 minutes) than short-acting insulins (within 30 - 60 minutes), therefore, the timing of the dose should be adjusted Rapid-acting insulins have a shorter duration of action than short-acting insulins (3 - 5 hours vs 6 - 8 hours). Because of this, patients switching to rapid-acting insulins from short-acting insulins may require more basal insulin to maintain blood sugar control, and vice versa. Conversions for inhaled insulin are discussed here - inhaled insulin dosing
Lantus, Semglee, Basaglar, Levemir, and Tresiba Dose remains the same when switching between Lantus, Semglee, Basaglar, Levemir, and Tresiba Patients at high risk for hypoglycemia may want to reduce the initial dose of the new insulin by 10 - 30% In trials comparing Tresiba to Lantus and Levemir, the glucose-lowering effect of Tresiba was equivalent to both insulins [22]
Lantus/Basaglar/Semglee ⇄ NPH Once-daily NPH to Lantus/Semglee/Basaglar Dose remains the same Twice-daily NPH to Lantus/Semglee/Basaglar Lantus/Semglee/Basaglar dose is 80% of total daily NPH dose Example: Patient's NPH dose is 30 units twice daily Total daily NPH dose is 60 units To convert to Lantus/Semglee/Basaglar: 60 units X 0.80 = 48 units Daily Lantus/Semglee/Basaglar dose will be 48 units [19] Lantus/Semglee/Basaglar to once-daily NPH Dose remains the same For patients who are at risk for hypoglycemia, consider an initial dose reduction of 20 - 30% to account for the peak effect that occurs with NPH. See converting from long-acting insulin to NPH for more. Lantus/Semglee/Basaglar to twice-daily NPH When switching from Lantus/Semglee/Basaglar to twice-daily NPH, it can be anticipated that a higher amount of NPH may be needed in order to achieve an equivalent effect In most patients, leaving the dose the same and retitrating as needed will be appropriate. Patients at high risk for hypoglycemia (e.g. concomitant premeal insulin) may want to reduce their initial NPH dose by 10 - 30%. See converting from long-acting insulin to NPH and twice-daily NPH for other considerations when changing to NPH insulin
Lantus/Semglee/Basaglar ⇄ Toujeo Lantus/Semglee/Basaglar to Toujeo When going from Lantus/Semglee/Basaglar to Toujeo, the daily dose remains the same Expect that a higher daily dose of Toujeo will be needed to maintain the same level of glycemic control as an equivalent dose of Lantus/Semglee/Basaglar In a multidose study, the glucose-lowering effect of Toujeo was about 27% lower than that of an equivalent dose of Lantus [21] Toujeo to Lantus/Semglee/Basaglar When going from Toujeo to Lantus/Semglee/Basaglar, the Lantus/Semglee/Basaglar dose should be started at 80% of the Toujeo dose in order to avoid hypoglycemia Lantus/Semglee/Basaglar is more potent than Toujeo; therefore, an equally effective Lantus/Semglee/Basaglar dose will likely be lower [19,23] Example: Patient's Toujeo dose is 60 units a day To convert to Lantus/Semglee/Basaglar: 60 units X 0.80 = 48 units Daily Lantus/Semglee/Basaglar dose will be 48 units
Levemir and NPH NPH to Levemir Daily dose remains the same Levemir to once-daily NPH Dose remains the same For patients who are at risk for hypoglycemia, consider an initial dose reduction of 20 - 30% to account for the peak effect that occurs with NPH. See converting from long-acting insulin to NPH for more. Levemir to twice-daily NPH When converting from Levemir to twice-daily NPH, an initial dose reduction of 20 - 30% may be appropriate in some type 2 diabetics. In a study where twice-daily Levemir was compared to twice-daily NPH, NPH doses of 0.52 units/kg had the same effect as Levemir doses of 0.77 units/kg. [20] See converting from long-acting insulin to NPH and twice-daily NPH for other considerations when changing to NPH insulin
Toujeo and NPH Once-daily NPH to Toujeo Dose remains the same Twice-daily NPH to Toujeo Toujeo dose is 80% of total daily NPH dose Example: Patient's NPH dose is 30 units twice daily Total daily NPH dose is 60 units To convert to Toujeo: 60 units X 0.80 = 48 units Daily Toujeo dose will be 48 units [19] Toujeo to once-daily NPH Dose remains the same For patients who are at risk for hypoglycemia, consider an initial dose reduction of 20 - 30% to account for the peak effect that occurs with NPH. See converting from long-acting insulin to NPH for more. Toujeo to twice-daily NPH Daily dose remains the same. Patients at high risk for hypoglycemia (e.g. concomitant premeal insulin) may want to reduce the initial NPH dose by 10 - 30%. See converting from long-acting insulin to NPH and twice-daily NPH for other considerations when changing to NPH insulin
Toujeo and Levemir Once-daily Levemir to Toujeo Daily dose remains the same [21] Twice-daily Levemir to Toujeo Toujeo dose is 80% of total daily Levemir dose Example: Patient's Levemir dose is 30 units twice daily Total daily Levemir dose is 60 units To convert to Toujeo: 60 units X 0.80 = 48 units Daily Toujeo dose will be 48 units [21] Toujeo to once-daily Levemir Daily dose remains the same [21] Toujeo to twice-daily Levemir Daily dose remains the same. Patients at high risk for hypoglycemia (e.g. concomitant premeal insulin) may want to reduce their initial Levemir dose by 10 - 30%.
Tresiba and Toujeo Tresiba to Toujeo Dose remains the same when switching from Tresiba to Toujeo Expect that a higher daily dose of Toujeo will be needed to maintain the same level of glycemic control as an equivalent dose of Tresiba In a multidose study, the glucose-lowering effect of Toujeo was about 27% lower than that of an equivalent dose of Lantus. Lantus and Tresiba have similar glucose-lowering effects. [21] Toujeo to Tresiba Reduce initial Tresiba dose by 20 - 30% to avoid hypoglycemia. In trials, the glucose-lowering effect of Toujeo was about 27% lower than that of Lantus. Lantus has a similar effect to Tresiba.
Tresiba and NPH NOTE: the manufacturer of Tresiba makes no specific recommendations when switching between NPH and Tresiba. The recommendations presented here are based on the fact that Tresiba has similar glucose-lowering effects as Lantus. Once-daily NPH to Tresiba Dose remains the same Twice-daily NPH to Tresiba Tresiba dose is 80% of total daily NPH dose Example: Patient's NPH dose is 30 units twice daily Total daily NPH dose is 60 units To convert to Tresiba: 60 units X 0.80 = 48 units Daily Tresiba dose will be 48 units [19] Tresiba to once-daily NPH Dose remains the same For patients who are at risk for hypoglycemia, consider an initial dose reduction of 20 - 30% to account for the peak effect that occurs with NPH. See converting from long-acting insulin to NPH for more. Tresiba to twice-daily NPH When switching from Tresiba to twice-daily NPH, it can be anticipated that a higher amount of NPH may be needed in order to achieve an equivalent effect In most patients, leaving the dose the same and retitrating as needed will be appropriate. Patients at high risk for hypoglycemia (e.g. concomitant premeal insulin) may want to reduce their initial NPH dose by 10 - 30%. See converting from long-acting insulin to NPH and twice-daily NPH for other considerations when changing to NPH insulin

CARBOHYDRATE INFORMATION

Carbohydrates and insulin

It's important that diabetics who are taking insulin monitor their carbohydrate intake
See the links below for more information on dieting and carbohydrates

Carbohydrate counting - review of carbohydrate counting used in dosing premeal insulin
Calories - review on calculating caloric requirements
Diabetic diet - diabetic diet recommendations
Carbohydrates - review of different carbohydrates found in foods

BIBLIOGRAPHY

1 - PMID 18945920
2 - PMID 10332663
3 - PMID 18364392
4 - Braithwaite S: Case Study: Five Steps to Freedom: Dose Titration for Type 2 Diabetes Using Basal-Prandial-Correction Insulin Therapy. Clinical Diabetes Vol 23:1 p39-43 2005
5 - Kulkarni K: Carbohydrate Counting: A Practical Meal-Planning Option for People With Diabetes. Clinical Diabetes Vol 23:3 p120-122 2005
6 - PMID 16915796
7 - PMID 15616254
8 - PMID 16921608
9 - PMID 10378067
10 - PMID 21193625
11 - PMID 12734137 - Outpatient Insulin Therapy in Type 1 and Type 2 Diabetes Mellitus, JAMA (2003)
12 - PMID 16847295
13 - Herbst K, Hirsch I Insulin Strategies for Primary Care Providers. Clinical Diabetes. Vol 20:1 p1-7 2002
14 - PMID 17890232 - NEJM DM 2 study
15 - Hirsch I et al. A Real-World Approach to Insulin Therapy in Primary Care Practice. Clinical Diabetes. Vol 23:2 p78-86. 2005
16 - PMID 18165339
17 - PMID 12766131
18 - Glucagon PI
19 - Lantus PI
20 - Levemir PI
21 - Toujeo PI
22 - Tresiba PI
23 - Basaglar PI
24 - ADA 2015 Standards of Medical Care in Diabetes, Vol 38, Supplement 1, p. S46
25 - PMID 29222370 - ADA 2018 Standards of Medical Care in Diabetes
26 - ADA 2019 Standards of Medical Care in Diabetes
27 - ADA 2020 Standards of Medical Care in Diabetes
28 - PMID 11926785 - Administration of neutral protamine Hagedorn insulin at bedtime versus with dinner in type 1 diabetes mellitus to avoid nocturnal hypoglycemia and improve control. A randomized, controlled trial, Ann Intern Med (2002)
29 - PMID 16160867 - Pharmacokinetic and glucodynamic variability: assessment of insulin glargine, NPH insulin and insulin ultralente in healthy volunteers using a euglycaemic clamp technique, Diabetologia (2005)
30 - PMID 16732007 - A 26-week, randomized, parallel, treat-to-target trial comparing insulin detemir with NPH insulin as add-on therapy to oral glucose-lowering drugs in insulin-naive people with type 2 diabetes, Diabetes Care (2006)
31 - 15298338 - Insulin analogues (insulin detemir and insulin aspart) versus traditional human insulins (NPH insulin and regular human insulin) in basal-bolus therapy for patients with type 1 diabetes, Diabetologia (2004)
32 - PMID 15111525 - Insulin detemir offers improved glycemic control compared with NPH insulin in people with type 1 diabetes: a randomized clinical trial, Diabetes Care (2004)
33 - PMID 11092282 - Appropriate Insulin Regimens for Type 2 Diabetes, Diabetes Care (2000)
34 - PMID 12882841 - Beneficial effects of insulin versus sulphonylurea on insulin secretion and metabolic control in recently diagnosed type 2 diabetic patients, Diabetes Care (2003)
35 - PMID 27278922 - Biphasic insulin Aspart 30 vs. NPH plus regular human insulin in type 2 diabetes patients; a cost-effectiveness study, BMC Endocr Disord (2016)

INSULIN DOSING