Sports + type 1 diabetes : What to keep in mind

Sports are key for this patient group. Hypoglycemia should be avoided by supplementing carbohydrate intake, preprandial and basal insulin doses reduction, and combining aerobic exercise with other activities.

Physical activity as the fourth pillar of metabolic control

For people with type 1 diabetes, it is important to be physically active, just like everyone else. Care should be taken to avoid hypoglycemia, which is achieved by supplementing carbohydrate intake, reducing the preprandial and basal dose of insulin, and combining aerobic exercise with other forms of activity. Tomasz Klupa, (Jagiellonian University Medical College, Krakow, Poland) gave these tips at a symposium held at the European Association for the Study of Diabetes's virtual Annual Conference in September 2020.

Patients with diabetes mellitus type 1 show increased symptoms of metabolic syndrome with increasing age. As a retrospective analysis of the DIVE (DIabetes Versorgungs-Evaluation) and DPV (Diabetes Patienten Verlaufsdokumentation) registries in Germany showed, blood pressure in type 1 diabetics increases with age, as does the use of oral antidiabetics and lipid-lowering drugs. In an American study, only 20% of type 1 diabetics were of normal weight and 80% were overweight or obese. According to a Swedish registry data, people with type 1 diabetes at a young age have a very high risk of cardiovascular death.

All this, says Klupa, proves that regular physical activity is very useful in this condition. Klupa is convinced that in addition to glycemic control, blood pressure, and lipid metabolism control, regular physical activity is the fourth pillar in the metabolic control of type 1 diabetics.

Advantages of regular physical activity

Regular physical activity improves the cardiovascular risk profile by improving body composition and helping to control body weight. Endothelial functions and lipid profiles improve and blood pressure targets are easier to reach.

Regular physical activity improves cardiorespiratory fitness and reduces the risk of cardiovascular complications such as coronary heart disease, heart attack, or stroke. Overall, regular physical activity helps reduce the risk of premature death.

In type 1 diabetics, HbA1c levels decrease and insulin sensitivity improves. The need for insulin decreases. Regular physical activity also reduces the risk of developing retinopathy and albuminuria.

Glycaemic responses to physical activity

In type 1 diabetics, the glycaemic response to physical activity depends on a number of factors, such as the patient's initial fitness level, the type of physical activity, the amount of insulin in the circulatory system, the blood glucose concentration before exercise, and the composition of the last meal or snack.

During aerobic activity, blood glucose levels fall for most diabetics, even if they consume carbohydrates, because the insulin concentration does not fall quickly enough. It can even rise in the systemic circulation because the subcutaneous fatty tissue is supplied with more blood during physical activity.

So to prevent hypoglycemia, people with type 1 diabetes have to supplement their carbohydrate intake and/or reduce their insulin dose before aerobic activity. Short sprints with maximum intensity delay the breakdown of glucose during moderately intensive activities, which can theoretically protect against hypoglycemia after exercise.

In a consensus statement, Michael C. Riddell and colleagues have put together many practical recommendations for type 1 diabetics who want to exercise.

Extreme sports

Extreme sports are also possible with type 1 diabetes. Klupa, for example, reported on four type-1 diabetics who took part in a mountain ultra-marathon. In none of the cases did they develop severe hypoglycemia because the marathon runners had reduced their insulin dose and increased their carbohydrate intake.

A 44-year-old type 1 diabetic took part in a non-stop cycling race over 3 days and 1,008 km. He used the MiniMed-640G system with Smart Guard, whose target level was set at 90 mg/dl. This effectively prevented hypoglycemia.

Before high mountain tours, it must be clarified whether pumps and sensors work reliably even at high altitudes and whether the insulin requirement changes. In a review paper, Pieter de Mol and colleagues have collected information on this extreme sport.

Martial arts are also possible for type 1 diabetics. For example, the Polish champion in Brazilian jiu-jitsu is just as much a type 1 diabetic as the Polish youth champion in weightlifting.

Symposium "Diabetes on the run: insulin therapy in type 1 diabetes and exercise", Virtual EASD Annual Meeting 2020, S39.