• References [1,2]
Carbohydrate adjustments for exercise
Pre-exercise glucose: < 90 mg/dl (< 5 mmol/L)
    Aerobic exercise (> 30 minutes)
    • Ingest 15 - 30 grams of a high glycemic index carbohydrate
    • Start exercise after blood glucose rises to > 90 mg/dl
    • Consume 0.5 - 1 gram of carbohydrate per kg body weight per hour of exercise (0.5 - 1 gram/kg/hour of exercise)
    Anaerobic exercise or short-duration aerobic (< 30 minutes)
    • Ingest 15 - 30 grams of a high glycemic index carbohydrate
    • Start exercise after blood glucose rises to > 90 mg/dl
    • Additional carbohydrates may not be necessary depending on prior insulin intake
Pre-exercise glucose: 90 - 150 mg/dl (5 - 8.3 mmol/L)
    Aerobic exercise (> 30 minutes)
    • Consume 0.5 - 1 gram of carbohydrate per kg body weight per hour of exercise (0.5 - 1 gram/kg/hour of exercise)
    Anaerobic exercise or short-duration aerobic (< 30 minutes)
    • Additional carbohydrates may not be necessary depending on prior insulin intake
Pre-exercise glucose: 150 - 250 mg/dl (8.3 - 13.9 mmol/L)
    Aerobic exercise (> 30 minutes)
    • Initiate exercise and delay carbohydrate intake until glucose levels are < 150 mg/dl
    • Consume 0.5 - 1 gram of carbohydrate per kg body weight per hour of exercise (0.5 - 1 gram/kg/hour of exercise)
    Anaerobic exercise or short-duration aerobic (< 30 minutes)
    • Additional carbohydrates may not be necessary depending on prior insulin intake
Pre-exercise glucose: 250 - 350 mg/dl (13.9 - 19.4 mmol/L)
  • Check for ketones (blood or urine). See ketone testing below.
  • If ketones are moderate-to-large (blood ≥ 1.5 mmol/L), do not exercise. Initiate appropriate insulin therapy and/or contact health professional.
  • If ketones are negative or small (blood < 1.5 mmol/L), initiate mild-to-moderate exercise. Delay intense exercise until glucose is < 250 mg/dl. Intense exercise may raise glucose levels.
Pre-exercise glucose: > 350 mg/dl (> 19.4 mmol/L)
  • Check for ketones (blood or urine). See ketone testing below.
  • If ketones are moderate-to-large (blood ≥ 1.5 mmol/L), do not exercise. Initiate appropriate insulin therapy and/or contact health professional.
  • If ketones are negative or small (blood < 1.5 mmol/L), consider giving corrective insulin dose at 50% of normal. Initiate mild-to-moderate exercise. Delay intense exercise until glucose is < 250 mg/dl. Intense exercise may raise glucose levels.



  • References [1,2]
Suggested reduction in bolus (premeal) insulin if given within 90 minutes prior to exercise
30 minutes of exercise Bolus insulin dose reduction
Mild aerobic -25%
Moderate aerobic -50%
Heavy aerobic -75%
Intense aerobic/anaerobic No dose reduction
60 minutes of exercise Bolus insulin dose reduction
Mild aerobic -50%
Moderate aerobic -75%
Heavy aerobic N/A
Intense aerobic/anaerobic N/A
Prevention of nocturnal hypoglycemia
(particularly for exercise performed in afternoon or evening)
For first meal after exercise (within 90 minutes)
  • Consider consuming 1.0 - 1.2 grams/kg of carbohydrates
  • Consider reducing bolus (premeal) insulin dose by ∼ 50%

  • References [1,2]
Suggested reductions in basal insulin for prolonged exercise (> 30 minutes)
General considerations
  • Prolonged anaerobic exercise may not require any insulin adjustments
  • Mixed activity (anaerobic + aerobic) might require smaller reductions in insulin. Performing anaerobic exercise before aerobic exercise may attenuate the hypoglycemia caused by aerobic exercise.
  • For strenuous prolonged aerobic exercise (e.g. marathon running, cycling, cross-country skiing), increased carbohydrate intake as opposed to insulin reduction may help improve performance

Patients using multiple injections a day
  • Consider reducing the basal insulin dose before prolonged exercise by 20%
  • If nocturnal hypoglycemia is a concern, consider reducing overnight basal insulin dose by 20%

Patients using insulin pumps
  • Option one
    • Consider suspending insulin pump during prolonged exercise. Use caution is suspending for more than an hour.
  • Option two
    • Reduce basal insulin by 50 - 80% up to 90 minutes before prolonged exercise



  • In type one diabetics, ketone levels > 1.5 mmol/L should be addressed immediately by checking glucose levels and administering corrective insulin
Blood value (mmol/L) Urine value
< 0.6 Negative
0.6 - 1.5 Small to moderate
1.6 - 3.0 Moderate to large
≥ 3.0 Large



  • References [2]
Glycemic index (GI) and exercise
Low GI foods
  • Consumption of low GI foods before exercise may help prevent hypoglycemia during prolonged activity
  • Consumption of a meal or bedtime snack with a low GI after afternoon exercise may help prevent nocturnal hypoglycemia for up to 8 hours
  • Low-to-moderate GI foods may be preferred for prolonged aerobic activity at low-to-moderate workloads
High GI foods
  • High GI foods can be used to prevent/treat hypoglycemia during aerobic activity
  • Consumption of high GI foods after exercise may enhance recovery