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## Carbohydrate Count in Insulin Dosing

*Aka: Carbohydrate Count in Insulin Dosing, Insulin Adjustment with Carbohydrate Counting*

- See Also
- Management: Step 1a - Determine Carbohydrate to Insulin ratio
- Determine total Insulin used per day
- Option 1: Known dose from multiple daily doses or Insulin Pump
- Option 2: Calculate based on patient weight
- Type I: Total daily Insulin (TDI)
- TDI = WtKg x 0.1 to 0.3 units/kg (start low)

- Type I: Total basal dose (TBD)
- TBD = WtKg x 0.2
- TBD = 0.4 x Total Daily Insulin (TDI)

- Type II: Total daily Insulin (TDI)
- TDI = WtKg x 0.3 units/kg: Underweight, advance age, Dialysis
- TDI = WtKg x 0.4 units/kg: Normal weight
- TDI = WtKg x 0.5 units/kg: Overweight
- TDI = WtKg x 0.6 units/kg: Obese, steroid use, high Insulin Resistance

- Type I: Total daily Insulin (TDI)
- Option 3: Simple carbohydrate based-method (below in Step Ib)

- Plan to split the basal Insulin and Bolus Insulin evenly (50% to each)
- Calculate Insulin to carbohydrate ratio or ICR (g carb per one unit Insulin)
- Calculate correction factor (CF)
- Blood Glucose drop expected per unit of Insulin (using the Insulin-carb ratio or ICR above)
- Formula
- CF = ICR * 4.5

- For example
- Given Insulin to carbohydrate ratio of 6 g carb/unit
- Blood Glucose would correct 27 mg/dl with one unit Insulin

- Interpretation
- Ratio is carbohydrate grams covered by 1 unit Insulin
- Type I Diabetes
- One unit per carbohydrate (15 grams) is typical
- Effect of one unit Insulin on Glucose lowering
- Typically 1 Unit Bolus Insulin lowers Glucose 20-60 mg/dl
- Estimate: 1800/(daily Insulin dose)

- Example
- Type I Diabetes patient weighs 110 kg and uses ~35 total units of Insulin per day (0.3 units/kg)
- One unit Insulin covers 500/35 or 14 g carbohydrates
- One unit Insulin would be expected to lower Glucose 1800/35 or 50 mg/dl (in Type I Diabetes Mellitus)
- Lantus: Takes 18 units of Lantus per day
- Lispro: Takes 16 units total (4 units for each of 3 meals and 2 units for each of 2 snacks)

- Determine total Insulin used per day
- Management: Step 1b - Alternative to Step 1a (Simple Method)
- Dietician directs grams of carbohydrate per meal
- Estimate Daily Energy Allowance (calories)
- Estimate percentage of calories in diet (50-60%)
- Calories per gram of carbohydrate = 4
- Calculate total daily carbohydrate grams
- Daily Carbs (grams) = (Total Calories x 0.5) / 4
- Example = (1800 x 0.5)/4 = 225 carbohydrate grams

- Spread out carbohydrate grams across meals
- Example: 70 grams per meal, and two 20 gram snacks

- Choose carbohydrate servings to meet needs
- Each serving contains 12-15 grams carbohydrate
- Choose servings from 3 groups
- Breads and starches
- Fruit
- Milk
- Vegetables are not counted

- Dietician directs grams of carbohydrate per meal
- Management: Step 2 - Predict carbohydrate effect on Serum Glucose
- Glucose rises at constant rate per gram carbohydrate
- Other modifiers of carbohydrate effect on Serum Glucose
- Glycemic Index
- Percentage of food from protein and fat

- Management: Step 3 - Count Carbohydrates
- Indications
- Techniques
- Food labels (use grams of carbohydrate per serving)
- Food tables (e.g. cookbooks, references)
- Food weight
- Determine Carb Factor for particular food
- Percentage of given food from carbohydrate

- Weigh food on gram scale
- Carbohydrate grams = (food weight) x (carb factor)

- Determine Carb Factor for particular food

- Management: Step 5 - Summary: Combining Insulin protocols
- Basal Insulin (Maintenance, covers between meals and ovenight)
- Once daily: Lantus
- Twice daily: Levemir, NPH Insulin

- Bolus Insulin (pre-meal Insulin, covers post-meal Blood Sugars)
- Units per carbohydrate of planned meal AND
- Units of Correctional Insulin Dosing based on Blood Sugars over 149 before the meal

- Example
- A 70 kg man with Type II Diabetes Mellitus
- Insulin Glargine (Lantus)
- Uses 14 units per day at dinner

- InsulinHumalog (Lispro) with coverage
- Uses 1 unit per carbohydrate PLUS 1 unit per 50 over 150
- Blood Sugar of 200 at lunch and having prepared a 4 carbohydrate meal
- Takes a total of 6 units: 4 units (4 carbs) plus an additional 2 units (for Blood Sugar of 200)

- Basal Insulin (Maintenance, covers between meals and ovenight)
- References