How Type I Diabetes Responds to Different Diets (Normoglucidic or Ketogenic) During Physical Activity at Altitude

To date, no study has shown the effects of diets (normoglucidic or ketogenic) on type I diabetes during physical activity (hiking, ski touring) at altitude.

Today, many sportsmen and women use the ketogenic diet (reproducing the effects of food fasting) because it improves physical performance. In particular, it avoids the undesirable effects of carbohydrate intake during re-sugaring (digestive level, fatigue, glycaemic peak) and reduces muscular fatigue.

Patients with type II diabetes also use this diet because insulin resistance decreases, weight loss is increased, and diabetes is balanced.

The ketogenic diet in the general population is increasingly studied scientifically, but no clinical trial has studied it in type I diabetic patients during physical activity at altitude. Similarly, no study has investigated the effects of this diet on ketone and blood glucose levels in athletes during physical activity at altitude.

Therefore, its impact on blood glucose and ketone levels during exercise at altitude is unknown in healthy and type I diabetic subjects.

Since the investigators are studying ketonemia at altitude, and since ketonemia depends on insulin and carbohydrate intake, it is necessary to also study a control group on the same diet, in order to analyse whether the results obtained at altitude are related to the diet alone or to the diet in the context of diabetes.

In order to avoid certain biases and confounding factors, the type I diabetic group will be compared to a control group of healthy subjects, in which the subjects have the same diet as the diabetic group.

This is a pioneering study, of significant interest because the ketogenic diet is recent and rapidly increasing in interest in diabetic patients, with no scientific data for mountain physical activity. Doctors, diabetologists and sports doctors, are still without data to advise their diabetic patients who wish to follow a ketogenic diet on the benefits/risks of this diet, or to explain to them how to react to physical activity in the mountains.

The main objective is the effect of normoglucidic and ketogenic diets on diabetic parameters (blood glucose and ketone levels) during physical activity at altitude in type I diabetics in comparison with the control group.

The secondary objective is to evaluate the effect of diets (normoglucidic or ketogenic) on physical skills during a physical activity (hiking, ski touring) at a peak altitude during the outing at 2000m and 2500m in both groups.

Each participant must agree to take part in 2 mountain physical activity outings at 2000m and 2 outings at 2500m. The physical activity must be similar in nature (hiking or skiing) and pace.

All outings are supervised (by the Diamachro association and the co-investigator for the diabetes group and by the co-investigator for the control group).

the sequence of the 4 outings will be the same, including blood glucose and ketone measurements, heart rate and oxygen saturation measurements, as well as the completion by the subject of the food collection and the Borg scale.

After the data have been collected, they will be analysed by the investigator

Inclusion criteria

For the diabetes group:

• Major subjects with type I diabetes, enrolled in the Diamachro association in conjunction with the diabetology department of the Centre Hospitalier Métropole Savoie in Chambéry
• treated with insulin in basal/bolus form or on pump
• regularly (>2x/month) doing physical activity (hiking or ski touring) at altitude (>1500m)
• agreeing to make 4 mountain outings (hiking or ski touring): 2 at an altitude of 2000m and 2 at an altitude of 2500m
• be affiliated to, or benefit from, a health insurance scheme.

For the control group:

• major subjects with no known endocrine pathology.
• Regularly (>2x/month) engaged in physical activity (hiking or ski touring) at altitude (>1500m)
• agreeing to do 4 mountain outings (hiking or ski touring): 2 at an altitude of 2000m and 2 at an altitude of 2500m
• be affiliated to, or benefit from, a health insurance scheme.
• healthy adults who usually go out in the mountains

Exclusion criteria

For the diabetes group:

• minor subject
• subject with diabetes other than type I diabetes
• adult under guardianship, curatorship, or judicial protection

For the control group:

• minor subject
• adult under guardianship, trusteeship, or court protection