Insulin Adjustments

These "Desktop Insulin Adjustment Guidelines" originally existed on paper but are now available on your electronic "desktop" for when you need them. As always, consider individual client needs and your clinical judgment.

Variables 

Consider the following prior to adjustment of insulin, as solutions might exist here:

  • Psychosocial considerations e.g. What's the hardest part about giving insulin? 
  • Basal doses taken vs. prescribed 
  • Carb ratios used in examples vs. prescribed vs. reported (It's not unusual for people to report one ICR out of habit, yet when describing how they determined their bolus dose at a specific meal report using a different ICR.)
  • Consistent use of correction dose
  • Target patient is correcting to (used in an example by patient)
  • Current A1c vs A1c target
  • Missed injections
  • When insulin is taken (ac or pc)
  • Lifestyle changes possible vs. med changes (if appropriate given A1c)
  • Sites - location and usage (lipohypertrophy?)
  • Intramuscular injections (avoiding 12 mm pen needles)
  • Correct use of delivery device (pushing plunger, not dialing it back to zero)
  • Insulin expiry, time at room temp 
  • Diet change
  • Weight change
  • Physical activity change
  • Illness or stress 

 

Basic Insulin Adjustment Table

 DCC basic insulin adjustment 2019

 If almost all readings are high, see options below for high everywhere. If numerous lows over the day, see options below in hypoglycemia.

Table adapted from Alberta Health Services Basal Bolus Insulin Therapy (bbit.ca).

 

Basal Insulin Adjustment

  1. For basal insulin only (no bolus insulin prescribed)
    • Evening basal insulin is usually adjusted until morning glucose readings are in target. However, this pattern may not always hold with ultra-long acting basal insulins. Adding basal insulin to oral/injectable agents is a gentle way to add in insulin to bring glucose readings into target with less weight gain and hypoglycemia than starting with bolus/meal insulin first.
    • Adjustment notes:
      • 1 unit per day till in target (Diabetes Canada)
      • 2 units or 10% every 1-2 days is common advice for patient self-adjustment (or 3 days for some ultra-long insulins)
      • 10-20% or greater is a frequent guideline for clinicians
      • Consider glycemic responses to past adjustments.
      • Consider BBIT formula for starting basal insulin.  E.g. 100 kg patient started on 10 units basal insulin, but no significant drop in glucose readings afterwards. Consider more than 10% increase given that the formula suggests a starting dose of 10-20 units.
      • As doses increase, focus on the percent adjustment. A 2 unit increase on 40 units is only a 5% adjustment.  
      • Consider adding bolus insulin once basal dose exceeds 0.5 units/kg. 
  2. For basal + bolus insulin 
    • Adjust basal dose to hold glucose readings stable (within approx 2 mmol/L) from bedtime to morning, assuming no evening snack is eaten.
    • If an evening snack is eaten, remember that overnight and morning readings may also be impacted by that evening bolus (or lack of bolus).

Bolus Insulin Adjustment

Use the Basic Insulin Adjustment Table or the other methods on this page to determine which meal bolus insulin needs adjusting.

  1.  Adjusting "Set" Meal Boluses
    • Adjust the dose by 10% or as deemed appropriate. Consider how the last adjustment worked. If the patient is new to bolus insulin, consider referencing the BBIT formula for starting bolus insulin to be sure the dose is minimally adequate.

    • If an increase is needed at a meal, consider adding the correction dose from the following meal. (Or reworded, if high readings at a mealtime, take the units of correction dose and add to the previous meal's bolus dose.)

      e.g. Mrs. Wurther gives set meal boluses of  
      B'fast:    5 units + correction
      Lunch:   5 units + correction
      Supper: 9 units + correction
      (Correction of 1 unit for every 2 mmol/L above target of 7 mmol/L)

      Lunch readings: 5-7 mmol/L (gives 5 units for meal) 
      Supper readings: 13 mmol (gives 9 units for meal + 3 units correction). 
      The new set meal dose at lunch would be 5 + 3 = 8 units.
      Going forward, at lunch she would give 8 units + correction.
  2. Adjusting Insulin to Carbohydrate Ratios (ICR) 

    • If LOW afterwards, increase the carb part of the ICR.
      ICR = 1:8, consider new ICR = 1:9 or 1:10
      ICR = 1:10 consider new ICR = 1:12
      ICR = 1:12 consider new ICR = 1:15
      ICR = 1:15 consider new ICR = 1:20

    • If HIGH afterwards, reduce the carb part of the ICR. 
      ICR = 1:20 consider new ICR = 1:15
      ICR = 1:15, consider new ICR = 1:12
      ICR = 1:12, consider new ICR = 1:10
      ICR = 1:10 consider new ICR = 1:9 or 1:8
      ICR = 1:9, consider new ICR = 1:8

    • OR - If HIGH afterwards, consider adding the correction dose from the following meal. (Or reworded, if highs at a mealtime, take the units of correction dose and add to the previous meal's bolus dose.)

      e.g. Mr. Toystore, Target: 7 mmol/L
      ICR 1:10 for all meals
      ISF 2
      Supper: 4-7 mmol/L, 60 g carb common, 6 units meal bolus 
      Bedtime: 13 mmol/L (no snack) + 3 units correction

      The new supper ICR = 60 g carb divided by 9 units (6+3)= approx 7 
      Going forward, his ICR is 1:10 at breakfast; 1:10 at lunch: 1:7 at supper

    • OR - If HIGH at ALL meals and you've determined that the ICR at all meals needs to change based on the basal/bolus split, consider using the 500 rule as a reference (500/TDD=ICR). e.g. Bob's current ICR is 1:10. His total daily dose of insulin is 60 units. 500/60=8. HIs new ICR for all meals is 1:8. Remember, the use of this formula may not apply to each individual. 
  3. Adjusting Insulin Sensitivity Factor (ISF or Correction Factor)

    • Assess ISF by ...
      • comparing current ISF to formula for ISF (100/TDD) and/or
      • finding times where only correction insulin was used (no meal and no meal bolus) and/or
      • finding ac meal times above target and assessing subsequent readings (only if you've verified the meal bolus works when ac readings in target)
      • see examples of above on ISF page
    • Adjust ISF...
      • If giving hypoglycemic results, increase the number e.g. ISF 2 becomes ISF 3
      • If giving above-target results, decrease the number e.g. ISF 3 becomes ISF 2
    • For Adjusting a Correction Scale see our ISF page

Adjusting for Hypoglycemia

Patients often don't indicate events as "lows" because they have different definitions than educators. Consider asking, "How often are your readings below 4 mmol/L? How often are you are weak, shaky, sweaty?"  Remember to assess how they treat lows and the symptoms they have. These can change over time.

THREE OR MORE LOWS PER WEEK (less if elderly) or a SEVERE LOW. Options:

  1. Troubleshoot prevention of lows as the priority, even if there is a pattern of hyperglycemia. If there's been a severe low requiring the help of a third party, or there is hypoglycemia unawareness, set a higher glucose target. 
  2. If events are explainable (exercise, vacuuming etc, over-bolused, under-ate, alcohol, weight loss etc), ask patient about methods for preventing these lows
  3. If a pattern exists, reduce insulin most responsible per the basic insulin adjustment table (eg. lows before supper, reduce lunch bolus)
  4. If significant low readings over the entire day (low everywhere),
    • Consider basal insulin decrease (especially if basal insulin is > 60% of total daily dose of insulin (TDD). However, those on low CHO diet usually have an appropriately higher % basal.)
    • Consider bolus insulin decrease (especially if bolus insulin is > 60% of TDD)
  5. If lows follow high readings
    • Assess ISF to see if appropriate
    • Check that client is not stacking corrections (giving too many, too soon)
  6. If no pattern consider asking client to record meal, activity, dose etc. that come before each low to help problem-solve.
  7. If on a sliding scale, look to see if the lows are related to using one or two rows of the sliding scale. E.g. 11.1 -13 mmol/L range of the supper scale. See adjusting correction scales on ISF page. 

 

Adjusting for Hyperglycemia

OBVIOUS HIGH PATTERN e.g. mostly high at lunch. Options:

  1. Review insulin(s) affecting that time of day per the basic insulin adjustment table. Determine the best one to adjust. 
    e.g. if supper readings high:
    - increase lunch bolus OR
    - if in target at pm snack yet elevated before supper then add/increase snack bolus OR
    - if in target after lunch, no snack, elevated before supper then investigate increased afternoon basal insulin. 
  2. If adjusting a sliding scale, carefully consider if all of the glucose ranges on the scale ( e.g. 4-7, 7.1-9, 9.1-11, etc) need an adjustment, or if just a few of the ranges require an adjustment. See adjusting correction scales on ISF page.

HIGH EVERYWHERE e.g. few in target. Options:

  1. Consider addition of agents other than insulin such as an SGLT, GLP-1, metformin
  2. Consider increasing basal dose, especially if basal is less than 40%-60% TDD
  3. Consider increasing bolus insulins if basal is > 60% TDD
  4. Pick the highest of the high readings to target first
  5. Address fasting glucose first (supper bolus might need a change to prevent HS elevations; HS snack bolus might need a change)
  6. Increase one of the meal boluses, ideally patient's choice, to break the pattern or until a pattern appears.
  7. If a prescriber in hospital, consider increasing TDD by 10-20% and recalculating all Basal, Bolus and Correction Doses. (This may be a confusing strategy for outpatients who would then be using all new basal and bolus doses or formulas). 

 

Adjusting for Erratic Readings on Basal Bolus Insulin Therapy (BBIT)

In erratic glucose patterns, most meals have a fairly even mix of high and in-target readings. The following are suggested steps to follow. 

1: Assess overnight basal
2: Assess meal boluses 
3: Assess ISF

ERRATIC STEP 1:  Assess and adjust evening basal insulin to start the day in target.
Glucose readings that are stable (within approx 2 mmol/L) from evening to morning with no snack usually indicate appropriate overnight basal dosing. If not stable, adjust basal. 


ERRATIC STEP 2:  Determine if meal boluses are adequate for each meal. 

  1. Find pre-meal readings that are in target for each meal. If the subsequent readings are mostly...
    • in target (with no snack in-between) then the preceding meal bolus is reasonable. eg. B’fast 6.1 mmol →Lunch 7.1 mmol
    • elevated (with no snack in-between), then increase the preceding meal bolus or subtract carb from breakfast ratio.eg. B’fast 6.1 mmol →Lunch 8.9 mmol. Increase b’fast meal bolus or adjust ICR (e.g. 1:10 goes to 1:8)
    • low (with no snack and bolus), then decrease the preceding meal bolus or add carb to breakfast ratio. e.g. B’fast 6.1 mmol → Lunch 3.2 mmol. Decrease b’fast meal bolus or adjust the ICR (e.g.1:10 goes to 1:12)
    • elevated with a snack in-between, and the glucose reading before the snack is in target, then either the snack needs decreasing or the snack requires a bolus e.g. Breakfast 6.1 mmol; before snack 7.8 mmol (in target as 2 hr pc) and ac lunch 13.3 mmol.
  2. If only a few glucose checks and those are above target, find a dose that most often keeps the glucose readings stable from one meal to the next e.g. Breakfast 11.4 mmol with 7 units rapid total (meal bolus + correction) with result of lunch 12.5 mmol/L. In this case, it appears 7 units is appropriate for the new meal bolus. The correction dose would still need to be added to this new meal bolus.

ERRATIC STEP 3:  Assess Correction Insulin. Click for options listed above.