In France, more than 4 million people have type 2 diabetes, and just as many are estimated to be prediabetic without knowing it. Type 2 diabetes develops silently, often over years, before the first symptoms appear. And yet it's'one of the most preventable chronic diseases there is.
Regular physical activity acts directly on the biological mechanisms of type 2 diabetes: it improves insulin sensitivity, lowers blood sugar, reduces visceral fat mass and optimises glucose metabolism. A landmark study even shows it to be more effective than metformin (the first-line antidiabetic drug) at preventing the progression from prediabetes to diabetes. Here's'how.
1. Understanding type 2 diabetes: the rôle of insulin résistance
Type 2 diabetes is characterised by chronic hyperglycaemia, too much sugar in the blood, resulting from two mechanisms: insulin résistance (cells no longer respond properly to insulin) and the progressive exhaustion of the pancreas's beta cells, which produce insulin.
Insulin résistance develops gradually, often over 10 to 20 years, driven by sedentary behaviour, a high-glycaemic diet, excess weight (particularly visceral fat) and chronic stress. It's during this silent phase that intervention through physical activity is most effective.
| Stage | Characteristics | Opportunity for PA intervention |
|---|---|---|
| High risk | Overweight, sedentary behaviour, family history, high-normal blood sugar | Maximum: can fully prevent the development of prediabetes |
| Prediabetes | Fasting glucose between 1.10 and 1.25 g/L'or HbA1c between 5.7 and 6.4% | Very high: can normalise blood sugar and avoid progression to diabetes |
| Early type 2 diabetes | Fasting glucose above 1.26 g/L, HbA1c > 6.5% | High: can reduce HbA1c'and medication needs |
| Established diabetes | Ongoing drug treatment | Significant: improves glycaemic control and reduces complications |
2. How exercise affects blood sugar: the mechanisms
Physical activity is the most powerful glucose regulator after diet. It works through several complementary mechanisms:
- ●Glucose uptake by contracting muscle: during exercise, muscles take up glucose directly from the blood, independently of insulin (via GLUT4 transporters). Blood sugar drops immediately, an effect that persists for 24 to 48 hours after exercise.
- ●Improved insulin sensitivity: regular exercise increases the number and activity of insulin receptors in muscle and fat cells. As muscle becomes more receptive, the pancreas needs to produce less insulin for the same effect.
- ●Reduced visceral fat: deep abdominal fat is the main source of the free fatty acids responsible for insulin résistance. Aerobic exercise reduces it preferentially.
- ●Improved mitochondrial function: exercise stimulates mitochondrial biogenesis in muscle cells, improving their ability to use glucose as an energy source.
- ●Reduced chronic inflammation: low-grade inflammation is a central mechanism of insulin résistance. Regular exercise reduces inflammatory cytokines (IL-6, TNF-alpha) that disrupt insulin signalling.
3. The key numbers: exercise vs. medication
The Diabetes Prévention Program (DPP) study, published in the New England Journal of Medicine (Knowler et al., 2002), is the définitive référence in this field. It followed 3,234 people with prediabetes over 3 years, comparing three groups:
| Intervention | Réduction in diabetes risk | Secondary results |
|---|---|---|
| Placebo (no intervention) | Référence (0%) | Progression to diabetes in 29% of cases |
| Metformin (850 mg/day) | 31% réduction | Benefits limited to significantly overweight people |
| Lifestyle (PA + diet) | 58% réduction | Benefits independent of âge, sex and ethnicity |
The conclusion is striking: the lifestyle intervention (150 min of moderate physical activity per week plus a 7% loss of body weight) was almost twice as effective as the référence drug at preventing type 2 diabetes. And its effects persisted beyond the intervention period.
4. Which type of exercise for glucose metabolism?
The three types of exercise have complementary, synergistic effects on glycaemic régulation:
- ●Aerobic exercise (walking, cycling, swimming, jogging): the most studied for diabetes. It depletes glycogen stores and forces muscle uptake of blood glucose. The effect on blood sugar is immediate and lasts 24 to 48 hours.
- ●Strength training: increasing muscle mass increases glycogen storage capacity and the site of glucose uptake. A méta-analysis (Strasser et al., 2010) shows a 0.48% réduction in HbA1c'after 20 weeks of résistance training, clinically significant.
- ●Combining both: studies show that combining cardio and strength training produces effects superior to either modality alone for long-term glycaemic control.
- ●Active breaks during sedentary time: récent research shows that standing and walking for 2 to 3 minutes every 30 minutes reduces post-meal (postprandial) blood sugar by 30% compared with continuous sitting.
5. Physical activity and established diabetes: what to know
For people already diagnosed with type 2 diabetes, physical activity remains beneficial and recommended, with a few specific précautions:
- ●Monitor blood sugar before and after exercise: exercise can trigger hypoglycaemia in patients on insulin or sulfonylureas. A blood sugar target of 1.3 to 1.8 g/L before exercise is generally recommended.
- ●Start gradually: a 10-minute session after each meal is a very effective way to limit postprandial glucose spikes, and easy to fit into daily life.
- ●Get checked before starting: a health check-up with an exercise ECG is recommended for sedentary diabetic patients before starting an intense exercise programme, to screen for any silent cardiovascular complications.
A regular health check-up can assess your full metabolic profile, fasting glucose, HbA1c, lipid panel, waist circumference, and identify prediabetes early, before it progresses to diabetes. With physical activity as the first line of intervention, the room for prévention is considérable.
💡 Key tips
- Physical activity is almost twice as effective as metformin (the référence drug) at preventing the progression from prediabetes to diabetes, a 58% risk réduction vs. 31%.
- During exercise, muscles take up glucose directly from the blood, independently of insulin. Blood sugar drops immediately and the effect lasts 24 to 48 hours after exercise.
- Standing and walking for 2 to 3 minutes every 30 minutes reduces postprandial blood sugar by 30% compared with continuous sitting, an anti-diabetes habit anyone can adopt.
- Combining cardio and strength training is more effective than either alone for long-term glycaemic control. The two types of exercise are complementary.
- A health check-up can detect prediabetes early (often symptomless) and help set up a préventive physical activity programme before the disease takes hold.
Sources and références
- ●Knowler WC et al., Réduction in the incidence of type 2 diabetes with lifestyle intervention or metformin (NEJM, 2002)
- ●Colberg SR et al., Physical activity/exercise and diabetes: a position statement (Diabetes Care, 2016)
- ●Strasser B et al., Résistance training in the treatment of the metabolic syndrome (Sports Medicine, 2010)
- ●Dunstan DW et al., Breaking up prolonged sitting reduces postprandial glucose and insulin responses (Diabetes Care, 2012)
- ●WHO, Guidelines on physical activity and sedentary behaviour (2020)
- ●INSERM, Type 2 diabetes: prévention and treatment (2021)
