Simple explanation

This calculator estimates how much rapid-acting insulin may still be active at the planned start of activity. You enter body weight, current glucose, glucose trend, exercise type, and recent bolus doses.

It then combines insulin exposure, current glucose and exercise type to estimate a carbohydrate starting amount for 30 minutes of activity.

Practical interpretation

In simple terms, the higher the circulating insulin exposure, the higher the likely risk of glucose dropping during activity and the more carbohydrate may be needed.

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

The carbohydrate framework is for 30 minutes of activity. Trend is then applied as a final modifier:

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

For glucose above 15.0 mmol/L the framework gives 0 g carbohydrate. This does not assess ketones.