Family practice notebook

Posted on June 8, 2010

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Saskatchewan Insulin Dose Adjustment Module – March 2009

Family practice notebook

Insulin

  • Insulin Selection
  • Agents: Bolus Insulins (Meal-time Insulin)
  • Agents: Basal Insulins
  • Combination Agents (Type II Diabetes if poor compliance)
  • Adverse Effects
  • · References
  1. New insulin anologues are preferred
    1. More consistent absorption than traditional insulin
    2. Bolus analogues have more rapid onset
    3. Basal agents release at more constant rate
    4. Only disadvantage is anologues double price
  2. Combination agents are discouraged unless noncompliant
    1. Reduces flexibility in meal and activity timing
  1. Traditional Insulins
    1. Regular Insulin (Novolin R, Humulin R)
      1. Onset: 15 to 30 minutes
      2. Peak: 2.5 to 5 hours
      3. Duration: 6 to 8 hours
  2. Analogue Insulins (Rapid, consistent absorption)
    1. Glulisine (Apidra)
      1. Onset: 5 to 15 minutes
      2. Peak: 1 to 2 hours
      3. Duration: 3 to 5 hours
      4. Similar to other bolus analogues
      5. FDA approved to take after meal
        1. Other analogues expected with same effect
    2. Lispro (Humalog)
      1. Onset: 5 to 15 minutes
      2. Peak: 1 to 2 hours
      3. Duration: 3 to 5 hours
    3. Aspart (Novolog)
      1. Onset: 5 to 15 minutes
      2. Peak: 1 to 2 hours
      3. Duration: 3 to 5 hours
  1. Traditional Insulins
    1. NPH Insulin, Novolin N, Humulin N, Humulin L (Lente)
      1. Onset: 1 to 2 hours
      2. Peak: 6 to 8 hours
        1. Peak time is higher risk of hypoglcemia
        2. Consider snack at 6 hours after dose
      3. Duration: 10 to 16 hours (Lente slightly longer)
      4. Humulin L (Lente) discontinued in U.S. in 2006
    2. Ultralente Insulin (extended insulin zinc suspension)
      1. Discontinued in U.S. in 2006
      2. Significant inconsistent effect even in same person
      3. Onset: 6-10 hours
      4. Peak: No peak
      5. Duration: 18 to 24 hours
  2. Analogue Insulins
    1. Detemir (Levemir)
      1. Onset: 1 to 2 hours
      2. Peak: No peak (flat action curve)
      3. Duration: 12 to 20 hours (varies by dosage)
    2. Glargine (Lantus)
      1. Onset: 1 hour
      2. Duration: 21 to 24 hours
      3. Peak: No peak (flat action curve mimics continuous Insulin Infusion)
  1. NPH 50/Regular 50
  2. NPH 70/Regular 30 (Humulin 70/30 or Novolin 70/30)
  3. NPL 75/Lispro 25 (Humalog Mix 75/25)
  4. NPH 70/Aspart 30 (Novolog Mix 70/30)
  1. Hypoglycemia
    1. Increased risk when Hemoglobin A1C <7.4%
    2. Decreased risk with analogue insulins
  2. Weight gain (Excess of 4 kg over 10 years)
    1. Countered with Metformin in type 2 diabetics
    2. Countered with diet and Exercise
    3. Benefits of glucose control outweigh weight risks
  3. Lipohypertrophy
    1. Localized fat hypertrophy when sites not rotated
    2. Prevent by rotating injection sites (see below)
    3. Medical providers should examine injection sites
  4. Variable insulin absorption
    1. Insulin absorption varies by body site
      1. Abdomen (best absorption)
      2. Arms
      3. Thigh
      4. Buttocks (least absorption)
    2. Site rotation (prevents lipohypertrophy – see above)
      1. Rotate injections within same body region
        1. Avoids insulin absorption variability
      2. Rotate to widely different sites within region
        1. Example: Abdomen rotate to LUQ, RUQ, LLQ, RLQ
  1. Lepore (2000) Diabetes 49:2142
  2. Mayfield (2004) Am Fam Physician 70(3):489

Insulin Dosing

  • Goal Blood Glucose for Type I and Type II Diabetes
  • Evaluation: Blood sugars
  • ·  Evaluation: Adjustment of Insulin
  • ·  Resources
  1. Hemoglobin A1C <7%
  2. Goal: >50% of blood sugars in range
    1. Pre-meal Blood Glucose 70-120 mg/dl
    2. Two hour post-prandial Blood Glucose <160 mg/dl
    3. Bed-time Blood Glucose 100-140 mg/dl
  1. Monitoring pointers
    1. Be consistent in monitoring
    2. Aim for 50% of Blood Glucoses in target range
  2. Look for consistent pattern in blood sugars for >3 days
    1. Compare blood sugar for same time each day
    2. For each time of day:
      1. Calculate Blood Glucose range
      2. Calculate median Blood Glucose
    3. Consider eating and activity patterns during day
    4. Ignore spurious values
  3. Adjust only one Insulin dose at a time
    1. Correct Hypoglycemia first
    2. Correct highest blood sugars next
    3. Maintain a 50:50 mix of Basal to bolus Insulin
  1. Adjustment factors (for lows and highs)
    1. Adjust Insulin in small steps at a time
    2. Adjustment steps based on Insulin amount
      1. Insulin dose <10 units: Adjust by 1 unit
      2. Insulin dose 10-20 units: Adjust by 2 units
      3. Insulin dose >20 units: Adjust by 10% Insulin dose
    3. Adjustment steps based on diabetes type
      1. Type I Diabetes Mellitus: 1-2 units change
      2. Type II Diabetes Mellitus: 2-4 units change
  2. Correction protocol for Hypoglycemia
    1. General measures to consider
      1. Increase carbohydrate preceeding low
        1. Carbohydrate at prior meal or
        2. Snack or
        3. Pre-Exercise carbohydrate
      2. Adjust Exercise timing during the day
    2. Basal Insulin (e.g. Lantus) adjustment
      1. Blood Glucose low in AM
        1. Decrease basal Insulin (Lantus)
    3. Rapid acting Insulin (e.g. Lispro) adjustment
      1. Blood Glucose low before lunch
        1. Decrease rapid Insulin (Lispro) at breakfast
      2. Blood Glucose low before dinner
        1. Decrease rapid Insulin (Lispro) at lunch
      3. Blood Glucose low before bedtime
        1. Decrease rapid Insulin (Lispro) at dinner
  3. Correction protocol for hyperglycemia
    1. General measures to consider
      1. Decrease carbohydrate preceeding high
        1. Carbohydrate at prior meal or
        2. Stop or decrease snack
      2. Increase Exercise prior to meal
    2. Adjust Insulin based on Carbohydrate Count
      1. See Insulin Adjustment with Carbohydrate Counting
      2. One Unit covers each 10-15 grams carbohydrate
      3. Add 1-2 units for every 50 mg/dl glucose >150
    3. Indications to adjust basal Insulin (e.g. Glargine)
      1. All Blood Glucoses >200 mg/dl
        1. Increase basal Insulin by 0.1 units/kg
      2. All Blood Glucoses high (within 50 mg/dl)
        1. Increase basal Insulin per adjustment above
      3. Pre-supper Blood Glucose high
        1. Adjust basal Insulin per adjustment above
      4. Fasting (AM) Blood Glucose high
        1. Perform 3 am blood sugar checks
        2. Critical to distinguish 3 AM low BG from high BG
          1. Dawn Phenomena (relative Insulin deficiency)
            1. Increase basal Insulin by adjustment above
          2. Somogyi Phenomena (Rebound Hyperglycemia)
            1. Decrease basal Insulin by adjustment above
    4. Indications to adjust bolus Insulin (e.g. Lispro)
      1. Two hour post-prandial >40-60 mg/dl over premeal
        1. Increase rapid acting Insulin before meal
      2. Blood Glucose low before meal
        1. Decrease rapid Insulin before prior meal
  4. Average Insulin doses after titrating from start
    1. Type I Diabetes Mellitus: 0.7 units/kg
    2. Type II Diabetes Mellitus: 1.2 units/kg
  1. AIDA Diabetes Insulin Simulation
    1. http://www.2aida.org/online

Insulin Dosing in Type 1 Diabetes

  1. Dose: Initial Dosing with basal/bolus Insulin
    1. Calculate total daily Insulin (TDI) dose
      1. Ketones moderate or less: 0.5 units/kg/day
      2. Ketones large: 0.7 units/kg/day
    2. Divide total Insulin into basal and bolus dosing
      1. Basal Insulin (long-acting): 50% of total Insulin
        1. Insulin Glargine (Lantus) once daily (any time) or
        2. NPH Insulin twice daily
      2. Bolus Insulin (rapid acting): 50% of total Insulin
        1. Rapid acting Insulins: Lispro, Aspart
          1. Regular Insulin may be used instead due to cost
        2. Divide out equally before meals
        3. Adjust later for carb count variations at meals
    3. Example: 60 kg adult with moderate ketones
      1. Total Insulin dose: 30 units
      2. Divide Insulin
        1. Insulin Glargine (Lantus): 15 units at bedtime
        2. Insulin Lispro: 15 units total divided over meals
          1. Before breakfast: 5 units
          2. Before lunch: 5 units
          3. Before dinner: 5 units
  2. Dose: Conversion from mixed Insulin (70/30 or 75/25)
    1. Calculate total Insulin units
    2. Reduce total Insulin depending of Hemoglobin A1C
      1. Hemoglobin A1C >9%: Decrease total Insulin by 10%
      2. Hemoglobin A1C <9%: Decrease total Insulin by 20%
    3. Divide total Insulin into basal and bolus dosing
      1. Basal Insulin (long-acting): 50% of total Insulin
        1. Insulin Glargine (Lantus) once daily or
        2. NPH Insulin twice daily
      2. Bolus Insulin (rapid acting): 50% of total Insulin
        1. Rapid acting Insulins: Lispro, Aspart
        2. Divide out equally before meals
        3. Adjust later for carb count variations at meals
  3. Management: Adjustments
    1. See Insulin Dosing for adjustment regimen

Carbohydrate Count in Insulin Dosing

  • Step 1a: Determine Carbohydrate to Insulin ratio
  • Step 1b: Alternative to Step 1a (Simple Method)
  • Step 2: Predict carbohydrate effect on Serum Glucose
  • Step 3: Count Carbohydrates
  1. Determine total Insulin used per day
    1. Option 1: Known dose from multiple daily doses or Insulin pump
    2. Option 2: Calculate based on patient weight
      1. Type I: Total daily Insulin (TDI) = WtKg x 03 units/kg or (0.1 to 0.3 u/kg)
      2. Type II: Total daily Insulin (TDI) = WtKg x 0.1 units/kg or (o.1 ro 0.3 u/kg)
    3. Option 3: Simple carbohydrate based-method (below in Step Ib)
  2. Plan to split the basal Insulin and bolus Insulin evenly (50% to each)
  3. Calculate carbohydrate to Insulin ratio
    1. Short-acting rapid Insulin: Humalog (Lispro)
      1. Ratio = 500 / (total daily Insulin dose)
    2. Short-acting Insulin: Regular
      1. Ratio = 450 / (total daily Insulin dose)
  4. Interpretation
    1. Ratio is carbohydrate grams covered by 1 unit Insulin
    2. Type I Diabetes
      1. One unit per carbohydrate (15 grams) is typical
      2. Estimate glucose lowering of 1 unit = 1700/(total daily Insulin)
      3. Effect of one unit Insulin on glucose lowering
        1. Typically 1 Unit bolus Insulin lowers glucose 20-60 mg/dl
        2. Estimate: 1800/(daily Insulin dose)
  5. Example
    1. Patient uses 35 total units of Lispro per day
    2. One unit Insulin covers 500/35 or 14 g carbohydrates
  1. Dietician directs grams of carbohydrate per meal
    1. Estimate Daily Energy Allowance (calories)
    2. Estimate percentage of calories in diet (50-60%)
    3. Calories per gram of carbohydrate = 4
    4. Calculate total daily carbohydrate grams
      1. Daily Carbs (grams) = (Total Calories x 0.5) / 4
      2. Example = (1800 x 0.5)/4 = 225 carbohydrate grams
    5. Spread out carbohydrate grams across meals
      1. Example: 70 grams per meal, and two 20 gram snacks
  2. Choose carbohydrate servings to meet needs
    1. Each serving contains 12-15 grams carbohydrate
    2. Choose servings from 3 groups
      1. Breads and starches
      2. Fruit
      3. Milk
      4. Vegetables are not counted
  1. Glucose rises at constant rate per gram carbohydrate
    1. Weight 100 lbs: 1g carb raises glucose 5 points
    2. Weight 150 lbs: 1g carb raises glucose 4 points
    3. Weight 200 lbs: 1g carb raises glucose 3 points
  2. Other modifiers of carbohydrate effect on Serum Glucose
    1. Glycemic Index
    2. Percentage of food from protein and fat
  1. Indications
    1. Estimate Insulin needs per meal
    2. Plan meal to raise glucose to certain level
  2. Techniques
    1. Food labels (use grams of carbohydrate per serving)
    2. Food tables (e.g. cookbooks, references)
    3. Food weight
      1. Determine Carb Factor for particular food
        1. Percentage of given food from carbohydrate
      2. Weigh food on gram scale
      3. Carbohydrate grams = (food weight) x (carb factor)

Insulin Sliding Scale

  1. General
    1. Use this sliding scale as an example only
    2. Adjust per patient weight and activity or Disability
      1. Type I Diabetes Mellitus = 0.6 – 0.7 u/kg/d
      2. Type II Diabetes Mellitus = 0.3 u/Kg/d
  2. Disadvantages of Sliding Scale Insulin
    1. Reactive approach to blood sugar control
      1. Delays Insulin until hyperglycemia appears
    2. Does not meet basal Insulin requirements
    3. Promotes large swings in glucose control
  3. Protocol: Summary
    1. Cover as units per glucose 50 mg/dl over 150 mg/dl
    2. Adjust per condition
      1. Lower doses
        1. Low weight Type I Diabetes Mellitus
        2. Renal Failure (Insulin 50% renal excreted)
      2. Higher dose
        1. Large Type II Diabetes Mellitus
        2. Corticosteroid use
        3. Sepsis or severe illness
  4. Protocol 1: Based on Insulin sensitivity
    1. Basal Insulin should not be eliminated
      1. Applies even to those not eating
      2. Lantus should be continued at usual dose
      3. NPH Insulin
        1. AM dose: 50% of usual dose
        2. PM dose: 100% of usual dose
    2. Estimate sensitivity using “rule of 1800”
      1. BG change per unit Insulin = 1800/total Insulin daily
      2. Example of 60 units/day: 1 unit drops BG 30 mg/dl
    3. Protocol (uses rapid acting Insulin, e.g. Lispro)
      1. Goal Blood Glucose is <150
      2. Using sensitivity, how many units to drop 50 mg/dl
        1. For example above, ~1 unit to drop BG 50 mg/dl
          1. BG 150-199: 1 unit bolus Insulin (regular or RA)
          2. BG 200-249: 2 units bolus Insulin
          3. BG 250-299: 3 units bolus Insulin
          4. BG 300-349: 4 units bolus Insulin
          5. BG Over 350: 5 units bolus Insulin
        2. Add in coverage for meal intake
          1. Based on per carbohydrate when glucose >60 mg/dl
          2. Use for Type I Diabetes, consider for Type II
          3. Add to sliding scale coverage above
          4. Add 1 unit Insulin per carbohydrate
          5. Example: For 3 carbohydrate meal, add 3 units
  5. Protocols: Sliding Scales
    1. Very low schedule (Insulin-sensitive)
      1. BG 150-199: 0.5 unit bolus Insulin (regular or RA)
      2. BG 200-249: 1 units bolus Insulin
      3. BG 250-299: 1.5 units bolus Insulin
      4. BG 300-349: 2 units bolus Insulin
      5. BG Over 350: 2.5 units bolus Insulin
    2. Low schedule
      1. BG 150-199: 1 unit bolus Insulin (regular or RA)
      2. BG 200-249: 2 units bolus Insulin
      3. BG 250-299: 3 units bolus Insulin
      4. BG 300-349: 4 units bolus Insulin
      5. BG Over 350: 5 units bolus Insulin
    3. Medium schedule
      1. BG 150-199: 2 unit bolus Insulin (regular or RA)
      2. BG 200-249: 3 units bolus Insulin
      3. BG 250-299: 5 units bolus Insulin
      4. BG 300-349: 7 units bolus Insulin
      5. BG Over 350: 8 units bolus Insulin
    4. High schedule (Insulin-resistant)
      1. BG 150-199: 3 unit bolus Insulin (regular or RA)
      2. BG 200-249: 4 units bolus Insulin
      3. BG 250-299: 7 units bolus Insulin
      4. BG 300-349: 10 units bolus Insulin
      5. BG Over 350: 12 units bolus Insulin

Exercise in Diabetes Mellitus

  • Blood Sugar Management
  • Complications: Post-Exercise Hypoglycemia
  • Resources
  • References
  1. Check pre-Exercise blood sugar
    1. Blood sugar <100 mg/dl
      1. Snack 15-20 grams carbohydrate before Exercise
    2. Blood sugar 100 to 250 mg/dl
      1. No snack needed
    3. Blood sugar >250 with ketones (or >300 without)
      1. Delay Exercise
      2. Check Serum Ketones
      3. Treat hyperglycemia and dehydration
  2. Pre-Exercise Insulin
    1. Take Insulin more than 1 hour before Exercise
    2. Inject Insulin into a non-exercising site
      1. Absorption at abdomen is fastest and most reliable
    3. Decrease short-acting Insulin before Exercise
      1. Decrease 30% for Exercise less than 1 hour
      2. Decrease 40% for Exercise 1-2 hours
      3. Decrease 50% for Exercise over 3 hours
  3. Decrease risk of Hypoglycemia
    1. Avoid Exercise during times of peak Insulin activity
    2. Consider Humalog Insulin
    3. Insulin injection site may affect absorption rate
    4. Avoid Sulfonylurea
  4. Be aware of your own blood sugar response to Exercise
    1. Pre-Exercise Food
      1. Meals should be ingested 1-2 hours before Exercise
      2. Strenuous or prolonged Exercise
        1. Start increasing calorie intake 24 hours before
        2. Supplement carbohydrates every 30 minutes during
    2. Supplement during Exercise with glucose solutions
      1. One bottle for each 30 minutes strenuous Exercise
    3. Replenish glycogen stores after Exercise
      1. Based on Exercise duration and intensity
      2. Be aware of delayed Hypoglycemia
  5. Carry an activity pack while exercising
    1. Personal identification
    2. Mobile phone
    3. Adequate water and carbohydrate source
    4. Blood Glucose monitor
  1. Delayed Hypoglycemia
    1. Occurs 6 to 28 hours after strenuous Exercise
    2. Occurs despite normal blood sugars during Exercise
    3. Occurs regardless of age or illness severity
    4. Often occurs at night
  2. Mechanism
    1. Glycogen stores depleted and not replenished
    2. Increased Insulin sensitivity post-Exercise
  1. Diabetes, Exercise and Sports Association
  2. Mountains for Active Diabetics (extreme sports)
    1. http://www.mountain-mad.org
  1. Whaley (2006) ACSM’s Guidelines for Exercise
  2. White (1997) Lecture: AAFP Sports Medicine, Dallas
  3. Baraz (1994) Clin Diab 12(4):94
  4. Fahey (1996) Am Fam Physician 53:1611
  5. Landry (1992) Clin Sports Med 11:403

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