Are a combination of insulin injections and continuous pump better for patients with type 1 diabetes who partake in exercise?

This study examined which controlled blood glucose levels better in patients with type 1 diabetes (T1D) partaking in exercise – insulin pumps or a combination of insulin pumps and long-acting injections. The authors found that the combination was more effective for these patients.

Exercise has numerous benefits for patients with T1D. However, exercise interferes with blood glucose levels. To prevent low blood glucose (hypoglycemia) patients often disconnect their insulin pumps before exercise. While this is effective for many patients, some patients experience high levels of blood glucose (hyperglycemia) and can lead to complications such as ketoacidosis. 

It is possible that long-acting insulin injections, such as insulin degludec (Tresiba), could help patients because the insulin is not given continuously. The effectiveness and safety of combining long-acting insulin injections and an insulin pump for patients who exercise have not been investigated.

31 patients with T1D were divided into two groups. 14 patients used an insulin pump for 4 weeks before switching to insulin degludec injections and an insulin pump for another 4 weeks. 17 patients received the same treatments but in the reverse order. Patients underwent high and moderate-intensity exercise and disconnected insulin pumps 1 hour before exercise. Patients’ glucose levels were measured for 6 hours after exercise.

After moderate-intensity exercise, patients who used the combination for insulin spent 86 minutes longer in the target glucose range (4–10 mmol/L). Patients who used the combination spent 230 minutes in the target range compared to 143 minutes for patients who used an insulin pump only.

After moderate-intensity exercise, average glucose levels were 1.8 mmol/L lower in patients using the combination than those using an insulin pump. Patients using the combination spent 87 minutes less in a hyperglycemia range than those that used a pump only.

After high-intensity exercise, patients who used the combination for insulin spent 60 minutes longer in the target glucose range. Patients who used the combination spent 239 minutes in the target range compared to 179 minutes for patients who used an insulin pump only.

After high-intensity exercise, average glucose levels were 1.5 mmol/L lower in patients using the combination than those using an insulin pump.

After both moderate and high-intensity exercise, no differences were seen in the numbers of patients who developed hypoglycemia or severe hyperglycemia between groups. 

The authors concluded that a combination of insulin pump and long-acting insulin injections was an effective way to control glucose levels in patients with T1D who exercise.

The manufacturer of insulin degludec, Novo Nordisk, funded this study. This study would benefit from including more patients, particularly those less fit. Other types of exercise should also be investigated.

If you have concerns regarding insulin therapy and exercise, please discuss this with your doctor.