Physical activity and exercise
As for the general population, 150 minutes or more per week of moderate- or vigorous-intensity aerobic exercise is recommended for patients with type 1 diabetes.
The presence of complications associated with type 1 diabetes (eg retinopathy, peripheral neuropathy, autonomic neuropathy, cardiovascular disease) may influence the type of exercise that can be performed; seek advice from the multidisciplinary diabetes team. Seek advice also regarding management of blood glucose concentration around the time of exercise or other increased physical activity. This is challenging and needs to be individualised based on frequent blood glucose concentration monitoring.
The type and duration of exercise performed influences glycaemic response; blood glucose concentration tends to decrease with aerobic exercise and increase with resistance (anaerobic, strength) exercise.
The risk and fear of hypoglycaemia can be a major barrier to exercise in patients with type 1 diabetes. The increased risk of hypoglycaemia can last for at least 12 hours or longer after exercise, which can result in hypoglycaemia in the middle of the night (see Hypoglycaemia in patients with diabetes for management).
If aerobic exercise is anticipated, the patient may use one of the following approaches to avoid hypoglycaemia during or after exercise:
- eat 15 to 30 g of carbohydrate for every 30 minutes of moderate exercise
- decrease their insulin dose in relation to the anticipated intensity and duration of the exercise.
If aerobic exercise is expected to last more than 30 minutes, a decrease of insulin dose is preferred to an increase in carbohydrate intake.
Small studies have shown varied sequences of aerobic and resistance exercises performed in one exercise session affect blood glucose concentrations differently. Examples include:
- A brief (10 second) maximum intensity sprint before or after a moderate-intensity aerobic exercise session, or high-intensity bouts of exercise during moderate aerobic exercise, may slow blood glucose decline and protect against hypoglycaemia.
- Performing the resistance exercise first (in a session that includes both aerobic and resistance exercise) results in less hypoglycaemia than performing aerobic exercise first.
- High-intensity interval training (HIIT) (aerobic or resistance exercise) may not require any reduction in bolus insulin as the blood glucose concentration can initially rise after the activity.
A position statement about exercise is available from The American Diabetes Association1. For healthcare professionals and athletes with type 1 diabetes, information on a wide range of sports is available on the Runsweet website.