Calculating the bolus dose

As discussed, your insulin to carbohydrate ratio (ICR) tells you how much insulin your body needs in relation to the carbohydrate you eat. Everyone is slightly different but if you haven’t calculated your personal ICR (based on your current insulin doses (see the last section), then a starting ICR of 1:10 is a good place to begin. This means 1 unit of bolus insulin is needed for every 10 grams (1 CP) of carbohydrate.

10 grams of carbohydrate (1 CP) will roughly increase blood glucose levels by 2 – 3 mmol/L and 1 unit of bolus insulin will reduce blood glucose levels by the same amount.

Once you know your ICR and the total carbohydrate content of your meal, you can work out how many units of bolus insulin you need.

In the example above, the total carbohydrate content is 80g or 8 CPs. With an ICR of 1 unit for every 10 grams/1 CP, the required bolus dose is 8 units.

The ICR varies from person to person and can also be different for each meal. Discuss your own ICR with your diabetes care team and be prepared to make changes to your ICR if your blood glucose is regularly rising or falling too much after eating.