If diagnosed with prediabetes (elevated blood glucose below diabetes threshold), delay progression through dietary caloric restriction, weight loss, and increased physical activity; retest glucose every six months

For individuals with elevated blood glucose who have not yet reached the diagnostic threshold for diabetes, eating less, moving more, and losing a modest amount of weight reduces the risk of progressing to full diabetes by 30% to 60%. In China's 30-year Da Qing Diabetes Prevention Study, lifestyle intervention participants had a roughly 25% lower risk of all-cause mortality, living an average of 1.4 years longer. However, similar trials in the US and Finland did not observe statistically significant differences in all-cause mortality.

Zero financial cost; eating less saves a little money. Accumulate at least 150 minutes of moderate-intensity activity (such as brisk walking) per week, averaging ~20 minutes daily. Reduce daily caloric intake by 400 to 500 kcal compared to baseline. The primary difficulty is lifelong consistency and preventing weight regain once lost. Retest blood glucose every six months (fasting blood glucose costs ~10–20 yuan).

The Da Qing Diabetes Prevention Study was a clinic-randomized trial conducted in Da Qing, Heilongjiang Province, enrolling 577 adults with impaired glucose tolerance (a form of prediabetes) assigned to control or three 6-year intervention arms: diet alone, exercise alone, or combined diet plus exercise. Six-year cumulative diabetes incidence was 67.7% in controls versus 43.8% (diet), 41.1% (exercise), and 46.0% (combined). After adjusting for baseline BMI and fasting glucose, diabetes risk fell by 31%, 46%, and 42% respectively, with comparable reductions across lean and overweight subgroups (BMI cutoff 25). At 23-year follow-up, the combined intervention group had 41% lower cardiovascular mortality (HR 0.59, 95% CI 0.36–0.96), 29% lower all-cause mortality (HR 0.71, 95% CI 0.51–0.99), and 45% lower diabetes incidence (HR 0.55, 95% CI 0.40–0.76). At 30-year follow-up, median onset of diabetes was delayed by 3.96 years; composite cardiovascular events were 26% lower (HR 0.74, 95% CI 0.59–0.92), severe microvascular complications (retinopathy, nephropathy, neuropathy) were 35% lower (HR 0.65, 95% CI 0.45–0.95), cardiovascular mortality was 33% lower (HR 0.67, 95% CI 0.48–0.94), all-cause mortality was 26% lower (HR 0.74, 95% CI 0.61–0.89), and mean survival was prolonged by 1.44 years (95% CI 0.20–2.68). In the U.S. Diabetes Prevention Program (DPP) trial of 3,234 adults with prediabetes, the intensive lifestyle arm targeted >=7% weight loss and >=150 min/week physical activity: over a mean 2.8-year period, diabetes incidence fell by 58% (95% CI 48%–66%) compared to placebo, while metformin reduced incidence by 31% (95% CI 17%–43%). Over 15-year follow-up, lifestyle intervention maintained a 27% diabetes reduction (HR 0.73), though between-group divergence narrowed. At 21-year median follow-up, all-cause mortality (HR 1.02, 95% CI 0.81–1.28) and cardiovascular mortality (HR 1.18, 95% CI 0.77–1.81) showed no significant differences compared to controls. In the Finnish Diabetes Prevention Study (DPS) of 522 overweight adults with impaired glucose tolerance, lifestyle intervention reduced 4-year cumulative diabetes incidence by 58% (11% vs 23%), maintaining a 43% reduction at median 7-year follow-up; at 10.6 years, all-cause mortality showed no significant difference (HR 0.57, 95% CI 0.21–1.58). The Healthy China Action defines prediabetes as fasting plasma glucose 6.1 to 6.9 mmol/L and/or 2-hour post-load glucose 7.8 to 11.0 mmol/L, recommending overweight/obese individuals reduce BMI toward 24 or lose >=7% of body weight, cut daily caloric intake by 400–500 kcal, engage in >=150 min/week moderate-intensity exercise, and recheck fasting or 2-hour postprandial blood glucose every 6 months.

Controverted regarding mortality endpoints. All three major trials conclusively demonstrate reduced and delayed diabetes incidence; however, a statistically significant reduction in all-cause mortality was observed only in the Da Qing trial (which enrolled 577 participants, originally powered for diabetes incidence rather than mortality). In the U.S. DPP, once the randomized phase concluded, all arms including placebo were offered group lifestyle classes. In the Finnish DPS, statistical power for subtle mortality differences was limited. Therefore, delaying diabetes progression is firmly proven, while mortality extension remains an open question. Participants in the U.S. and Finnish trials had baseline BMI >30, whereas Da Qing participants averaged BMI 25.7, with notable benefits even in participants with minimal weight loss, suggesting dietary composition and physical movement drive benefits independently of mass reduction alone. Start by eliminating sugary drinks (Chapter 2, Rule 7). Activity targets are detailed in Chapter 2, Rule 11 (7,000–8,000 steps daily). BMI targets are outlined in Chapter 2, Rule 32 (BMI 20–25). Screening thresholds are described in Chapter 1, Rule 8 (fasting blood glucose screening). Metformin also delays diabetes onset but is less effective than lifestyle modification; its initiation requires medical prescription. Benefit magnitude is categorized as High based on the 26% reduction in all-cause mortality in the Da Qing trial. Primary beneficiary is yourself.

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