Type 2 diabetes is largely preventable: in two randomized trials, an intervention on diet and physical activity reduced its incidence by 58% in high-risk adults (Finland, 2001; United States, 2002). There are three pillars: knowing your risk factors, getting screened from age 45, and acting on your lifestyle.
Why prevent type 2 diabetes?
Type 2 diabetes is a common disease, on the rise and silent for a long time, whose complications affect the heart, arteries, kidneys, eyes and nerves. Preventing it means avoiding both the disease and its complications.
According to the French Federation of Diabetics (FFD), drawing on data from French National Health Insurance (Assurance Maladie), “more than 4.4 million people had diabetes in France in 2024,” with prevalence rising “from 5.5% in 2015 to 6.61% in 2024.” Type 2 diabetes accounts for 92% of cases, type 1 for 6% and other forms for 2%. Reimbursed spending on diabetes exceeded €11 billion in 2024 (FFD).
French National Health Insurance points out that type 2 diabetes “often progresses silently (with no symptoms at all) for several years,” because blood sugar rises gradually. This silence justifies targeted screening; this slowness leaves time to act.
What are the risk factors for type 2 diabetes?
The risk factors for type 2 diabetes combine a predisposition (age and family history) with lifestyle-related factors, foremost among them excess weight and lack of physical activity. French National Health Insurance is explicit: “excess weight and lack of physical activity are the main factors,” and “the family (or genetic) factor is not enough on its own; lifestyle is the main cause.”
| Risk factor | Benchmark (Assurance Maladie, HAS) | Modifiable? |
|---|---|---|
| Age | More common after 45 | No |
| Family history | A first-degree relative (father, mother, brother or sister) with type 2 diabetes | No |
| Overweight, obesity | BMI of 25 kg/m² or higher; waist circumference of 94 cm or more in men, 80 cm or more in women | Yes |
| Lack of physical activity, sedentary lifestyle | Less than 30 minutes of activity per day | Yes |
| High blood pressure | Treated or not | Partly |
| Lipid abnormalities | Triglycerides of 1.5 g/L or higher, low HDL cholesterol | Partly |
| Prediabetes | Fasting blood sugar between 1.10 and 1.25 g/L | Yes |
| History in women | Gestational diabetes, giving birth to a baby over 4 kg, polycystic ovary syndrome | No (but a warning sign) |
| Background, social situation | Non-Caucasian or migrant background; socioeconomic insecurity | No |
| Chronic smoking | Included by French National Health Insurance among the screening criteria | Yes |
Often overlooked, smoking increases the risk of type 2 diabetes by 37% to 44%, according to the FFD. Several of these factors (excess weight, high blood pressure, lipid abnormalities, borderline blood sugar) make up metabolic syndrome, which also increases cardiovascular risk; we cover it in our article on cardiovascular prevention.
How are type 2 diabetes and prediabetes screened for?
In France, the French National Authority for Health (HAS) recommends targeted opportunistic screening with a fasting venous blood sugar test in people over 45 with at least one risk factor, repeated every one to three years (periodic health examination guidance, validated in May 2014 and published in February 2015). French National Health Insurance specifies the frequency according to the result.
| Fasting venous blood sugar | Interpretation | Next steps (Assurance Maladie, based on the March 2014 HAS guide) |
|---|---|---|
| Below 1.10 g/L | Normal | Repeat test every 3 years; every 1 to 3 years if several risk factors are present |
| 1.10 to 1.25 g/L | Prediabetes (impaired fasting glucose) | Test every year; lifestyle measures |
| 1.26 g/L (7 mmol/L) or higher on two occasions | Diabetes | Confirmation with a second test, one month apart according to French National Health Insurance; care managed by your doctor |
| 2 g/L or higher at any time, with symptoms | Diabetes | Care without delay |
Glycated hemoglobin (HbA1c) is “a reflection of blood sugar over the last 3 months”; in France, it is used for the initial assessment and for monitoring, while fasting blood sugar remains the screening test recommended by the HAS. Prediabetes deserves particular attention: French National Health Insurance states that lifestyle changes can then bring blood sugar back to normal. We explain how to read these values in our article on blood sugar, HbA1c and prediabetes.
Which diabetes prevention programs have proven effective?
Two landmark randomized trials, one Finnish and one American, showed that a structured intervention on diet and physical activity reduces the incidence of type 2 diabetes by 58% in high-risk adults, and that some benefit persists fifteen years later.
| Study | Participants | Intervention | Result |
|---|---|---|---|
| Finnish Diabetes Prevention Study (Tuomilehto et al., NEJM, 2001) | 522 overweight adults with impaired glucose tolerance; mean age 55, mean BMI 31 | Individualized advice on diet and physical activity | Diabetes risk reduced by 58%; 4-year cumulative incidence of 11% vs. 23%; weight loss of 4.2 kg vs. 0.8 kg at one year; mean follow-up 3.2 years |
| Diabetes Prevention Program (Knowler et al., NEJM, 2002) | 3,234 non-diabetic adults with elevated blood sugar | Lifestyle program aiming for at least 7% weight loss and 150 minutes of physical activity per week, compared with metformin and placebo | Incidence reduced by 58% with lifestyle and 31% with metformin; mean follow-up 2.8 years |
| Diabetes Prevention Program Outcomes Study (Lancet Diabetes & Endocrinology, 2015) | Same cohort, followed for 15 years | Continued follow-up | Incidence reduced by 27% in the lifestyle group and 18% in the metformin group compared with placebo |
Three lessons. The 58% figure is a relative reduction in people already at high risk (prediabetes); it does not apply as such to the general population. The effect fades over time without disappearing: 27% less diabetes at fifteen years. Finally, these results came from structured, supported programs, not from simple advice. In France, a national type 2 diabetes prevention pilot program drew on these programs.
Which everyday levers: diet and physical activity?
The everyday levers are the same as in the trials: losing a few kilos if you are overweight, moving at least 150 minutes per week and rebalancing your diet. They can be discussed with your doctor or with the professional carrying out the prevention check-up, with no miracle diet.
Weight
The Diabetes Prevention Program aimed for a loss of at least 7% of initial body weight, or about 6 kg for a person weighing 85 kg. In the Finnish study, an average loss of 4.2 kg at one year already went along with a halving of risk. It is not thinness that protects, but the reduction in abdominal fat and insulin resistance.
Physical activity
The WHO recommends at least 150 minutes per week of moderate-intensity activity; French National Health Insurance speaks of “the equivalent of half an hour of brisk walking per day.” Less than 30 minutes of activity per day is explicitly listed among the risk factors for diabetes. Muscle strengthening and less sitting time complement endurance activity: muscle is a major consumer of glucose. Our benchmarks are detailed in physical activity for prevention.
Diet
The proven programs were based on a diet lower in saturated fat and fast-acting sugars and higher in fiber (vegetables, fruit, legumes, whole grains). The French National Health Insurance benchmarks (five servings of fruits and vegetables per day, fish twice a week, processed meats limited to 150 g per week) apply here just as they do for cardiovascular prevention, and cutting back on sugary drinks is one of the simplest steps. The principles are detailed in diet and nutrition for prevention.
Smoking and sleep
Quitting smoking removes a risk factor for diabetes on top of reducing cardiovascular risk; our article on quitting smoking describes the support available. Sleep and stress, which influence appetite and blood sugar, are part of the same conversation.
What does the prevention check-up at ages 45–50 identify?
Through the self-assessment questionnaire and the consultation, the prevention check-up offered between ages 45 and 50 inclusive identifies most of the risk factors for type 2 diabetes: excess weight, inactivity, diet, smoking, family history. It does not include a blood draw, but it results in a plan and, if needed, a referral to your regular doctor (médecin traitant) for a fasting blood sugar test.
The 30- to 45-minute consultation, fully covered (100%) by French National Health Insurance with no upfront payment, is carried out by a doctor, nurse, pharmacist or midwife and results in a Personalized Prevention Plan (PPP) setting one or two goals, which is sent to your regular doctor unless you object. The age of this check-up coincides with the 45-year threshold chosen by the HAS for screening: it is the time to ask for a blood sugar test if you have a risk factor. The process is described in the prevention check-up at ages 45–50 and the self-assessment questionnaire in the prevention check-up questionnaire.
What can a metabolomic profile add?
A nuclear magnetic resonance (NMR) metabolomic profile measures 249 biomarkers in a single sample, including glucose and other glycolysis metabolites, branched-chain amino acids, detailed lipoproteins and an inflammation marker. In the UK Biobank cohort, type 2 diabetes was among the eight diseases for which such a profile added 10-year predictive information to the full set of clinical variables, in 117,981 participants (Buergel et al., Nature Medicine, 2022).
These results apply to a research population; no French guideline incorporates metabolomics into diabetes screening, which relies on fasting blood sugar. Its value, discussed with your doctor, is to describe an intermediate metabolic profile in more detail and to track the effect of the changes you make. We detail these markers in our guide to blood biomarkers.
Key takeaways
- More than 4.4 million people were living with diabetes in France in 2024, 92% of them with type 2 (FFD, Assurance Maladie data); the disease progresses silently for years.
- The main modifiable risk factors are excess weight (BMI of 25 or higher, waist circumference of 94/80 cm or more) and lack of physical activity; age over 45 and first-degree family history form the underlying predisposition.
- The HAS recommends a fasting venous blood sugar test after 45 if a risk factor is present, every 1 to 3 years; 1.10–1.25 g/L defines prediabetes, and 1.26 g/L or higher on two occasions defines diabetes.
- The Finnish (2001) and American (2002) trials reduced the incidence of diabetes by 58% in high-risk adults through diet and physical activity; the effect persisted at 15 years (−27%).
- The prevention check-up at ages 45–50 identifies risk factors and points you toward a blood sugar test; metabolomics can refine the picture without replacing screening.
What Sokrate lets you do
The Sokrate service prepares your prevention check-up online: the Sokrate 360 adaptive questionnaire reviews weight, physical activity, diet, smoking and family history, then a doctor writes and signs your Personalized Prevention Plan, which is sent to your regular doctor unless you object; your regular doctor is responsible for prescribing a blood sugar test if indicated. The check-up, carried out by an authorized professional, is fully covered (100%) by French National Health Insurance, with no upfront payment. As an option and in agreement with your doctor, a metabolomics panel of 249 biomarkers can complement the check-up. Join the waitlist.