It has been known for several years that glucose is not passively taken up from the blood into the cell by a concentration gradient - but that an active mechanism is required for this: the so-called glucose-4-transporters (GLUT4), which are located in the cell membrane. In addition, there is a reservoir of vesicles within the cytoplasm with many more of these GLUT4 molecules.
A Danish study1 showed, with animal experiments, how it is possible to get these GLUT4 transports from the reserve vesicles into the membrane. For this purpose, rats muscles were isolated and several tests examined how the concentration of GLUT4 transports is taken up by 1. muscle contraction and by 2. insulin. The results show that both contraction and stimulation as well as insulin administration succeed in increasing the concentration in both cases. Both experiments show a significant increase in GLUT4 transport in the membrane.
To extend these test results to humans, researchers in another study2 examined five type 2 diabetes patients and 5 untrained non-patients using an open muscle biopsy from the vastus medialis muscle following a training period of several weeks. The results showed a significant increase in GLUT4 transport. Even after a single training result, it could be shown that physical activity doubles the concentration of GLUT4 in the cell membrane.
There is some scientific debate about why physical activity contributes to an increase in GLUT4 transport. The current working hypothesis is that it is probably the temperature of the muscle that helps to multiply glucose uptake.
Building on this, the EPIC study3 - a prospective cohort study from 2021 - investigated the relationship between cycling and mortality using 7459 diabetes patients. All sub-analyses showed the same pattern: the physically active group generally performed better than the untrained group.
The conclusion is that physical activity reduces the risk of cardiovascular disease and thus lowers the mortality rate in diabetes patients.
For many diabetes patients, the question arises again and again: What is the minimum I have to do to get the maximum effect?
Dr. Peter Kurz cites an Italian study entitled "Make Your Diabetic Patients Walk"4, which recorded the physical activity of 179 diabetes patients over a period of two years - extrapolated to the week.
The result was clear: a minimum of 35 minutes of walking already has a positive effect on the HbA1c value, the blood value and the cholesterol value. For the maximum effect, diabetes patients should walk 55-65 minutes a day.
Another randomised, controlled intervention study5 examined 251 type 2 diabetes patients (39-70 years) who were not active in sports and were not taking insulin therapy. They were divided into 4 groups with different exercise schedules. The endpoint was to observe how the HbA1c value developed after 6 months.
| Values | All | Baseline HbA1c > 7,5% |
|---|---|---|
| Control Group | 0,07 | -0,02 |
| Endurance | -0,30 | -0,49 |
| Strength | -0,43 | -0,83 |
| Endurance + Strength | -0,09 | -1,42 |
Dr. Kurz draws a clear conclusion: the ideal physical activity for diabetes remission includes both endurance and strength training.
The above results were even incorporated into the ESC Guidelines 2020, as diabetes patients are increasingly at risk of cardiovascular disease. The guidelines call for: strength training 3 times a week (at least) and moderate to demanding endurance training 5-7 days a week (30 minutes at a time).
Cluster 2: approx. 15-20%, congenital disorder of rapid insulin secretion
Cluster 3: approx. 15% genetic, severe insulin resistance (HOMA1 index >8)
Cluster 4: approx. 20% moderate to strong insulin resistance (HOMA1 index 3-6).
Cluster 5: 35-40%, mild to moderate insulin resistance (HOMA1 index 2-4)