Simple explanation

This calculator estimates how much glucose may fall during moderate activity when rapid-acting insulin is still active in the body.

You enter body weight, activity date and start time, current glucose, glucose trend, activity type, and recent bolus insulin doses. The calculator then estimates active insulin exposure and projects the likely glucose-lowering effect of moderate activity over 10, 20 and 30 minutes.

Practical interpretation

In simple terms, the more active rapid-acting insulin present at the start of activity, the larger the expected glucose-lowering effect.

Trend is then applied as a final modifier. Falling trends increase the estimate and rising trends reduce it.

Detailed explanation

Each bolus is converted into units per kilogram (U/kg). Larger doses are assumed to peak later and tail longer. Intermediate doses are interpolated between anchor points.

• 0.05 U/kg → peak about 1 hour, tail about 4 hours
• 0.10 U/kg → peak about 1.5 hours, tail about 6 hours
• 0.20 U/kg → peak about 2 hours, tail about 7 hours
• 0.30 U/kg → peak about 2.5 hours, tail about 8 hours

Estimated glucose lowering during activity is then scaled from active insulin exposure:

• 0.00 U/kg → about 0.025 mmol/L per minute
• 0.14 U/kg or above → about 0.20 mmol/L per minute
• Intermediate values are scaled linearly

Glucose trend is then applied as a final modifier:

• Falling fast: +30%
• Falling: +15%
• Stable: 0%
• Rising: −15%
• Rising fast: −30%

This is a physiology-based planning estimate, not a guaranteed prediction. It does not assess ketones. If glucose is high with little or no active insulin, activity may not lower glucose effectively.