The insulin start formulae below may be based on basal bolus insulin therapy (BBIT at http://bbit.ca/ ), Diabetes Canada Guidelines or accepted practice.
Basal Insulin Start
When basal insulin is added to non-insulin antihyperglycemic agents consider:
Diabetes Canada Guidelines: 10 units to start (individualized)
Conservative BBIT Guideline (DCC): 0.1 to 0.2 units/kg = units basal insulin
(e.g. approx. half of BBIT's most conservative TDD 0.3-0.5 u/kg, rounded down for ease)
- E.g. 100.0 kg X 0.1 or 0.2 = 10-20 units starting basal dose 100 kg client
- Tip: Take weight in kg and move decimal to the left for the LOWEST starting dose.
Double that number for the HIGHEST starting dose.
- Actual needs can be significantly higher, particularly in those who are resistant, however start conservatively.
To Adjust Basal Insulins: See Insulin Adjustment Page
Bolus Insulin Start
Diabetes Canada Guidelines: 2 - 4 units per meal
Conservative BBIT Guidelines (DCC): 0.05 - 0.1 units / kg = units per meal
- E.g. 100.0 kg X 0.05 or 0.1 = 5 -10 units
- Tip: Take weight in kg and move decimal to the left for the HIGHEST starting bolus dose per meal. Cut this in half for the LOWEST starting bolus dose per meal.
- When to start bolus: If on > 0.5 units basal insulin per kg and not at target, consider adding bolus soon (consider A1c, age, complexity, etc).
- Actual bolus needs can be significantly higher, particularly in those who are resistant, however start conservatively.
To Adjust Bolus Insulins: See Insulin Adjustment Page
Basal & Bolus Start
- Starting TDD = 0.5 - 1.0 units/kg/day
(0.3 - 0.5 u/kg/day if more sensitive to insulin; 0.5 - 1.0 u/kg/day if more insulin resistant)
- Daily basal insulin = 50% of TDD
- Daily bolus insulin = 50% of TDD (distributed amongst 3 meals)
- Or, if mixed insulin (e.g. 30/70) loosely 2/3 of TDD premix at breakfast and 1/3 at supper.
- Tip: If resistant consider this shortcut:
- half the weight in kg = total daily basal units
- half the weight in kg = total daily bolus units (distribute over 3 meals)
- Example for 100 kg resistant patient
- 50 units basal
- 50 units bolus
(50 / 3 meals = 16 units per meal but preferable to individualize.
e.g. if breakfast is small and supper large, then distribute it proportionately)
- To adjust for BBIT patterns (lows,highs,erratic) see Insulin Adjustment page.
Assessing % Basal in BBIT
- Total daily units basal / total daily units all insulin x 100 = % of insulin as basal
e.g. 45 units basal for the day / 90 units TDD x 100 = 50% of insulin as basal
- For most people, approximately 40-60% of their total daily dose of insulin (TDD) is basal insulin. This split varies for those on partial-closed-loop insulin pumps due to algorithms. For those with low carbohydrate diets, expect a higher % basal.
Insulin Sensitivity Factor (ISF) or Correction Dose
To create an ISF for RAPID insulin:
- 100/TDD = number of mmol/L 1 unit rapid will lower glucose level.
E.g. 100/50 units TDD = 2
1 unit will drop glucose by about 2 mmol/L
- *Note: If the forumula suggests ISF <2, consider ISF of 2 to start (it's safer). Fine tune later.
To create an ISF for REGULAR insulin:
- 83/TDD = number of mmol/L 1 unit regular insulin will lower glucose level.
E.g. 83/30 units TDD = about 3.
1 unit will lower glucose by about 3 mmol/L
To use an ISF:
- (Current Blood Glucose – target) / ISF= units to give to correct high glucose reading
- e.g. If current BG 13 mmol/L , ISF is 2 and target is 7 mmol then:
13 mmol/L - 7 mmol/L = 6 / ISF 2 = 3 units for correction
- To adjust ISF, see Insulin Adjustment page for short summary or ISF page for longer description with examples.
- To create and adjust a correction scale, see the related heading on the ISF webpage..
Carb Ratio (formerly termed Insulin to Carb Ratio or ICR)
To create a Carb Ratio:
- Method 1: Divide grams of available carbohydrate eaten for a meal by bolus dose (units) per same meal to determine the carb ratio
e.g. 70 g available carb eaten / 5 units rapid = 14. So Carb Ratio 14
Therefore, for every 14 g available carb eaten, 1 unit of bolus insulin is given
- Method 2: The 500 rule (500/TDD)
e.g. 500 / Total Daily Dose of insulin of 50 units = 10. So Carb Ratio = 10
Therefore, for every 10 g available carb eaten, 1 unit of bolus insulin is given
- For adjusting ICR, visit Adjusting Insulin Page