The role of age on the risk relationship between prediabetes and major morbidities and mortality: Analysis of the Hong Kong diabetes surveillance database of 2 million Chinese adults

BACKGROUND: Intensive lifestyle modification showed variable success in the prevention of major clinical events and mortality among people with prediabetes. We propose that age may partly explain the heterogeneity and that health hazards related to prediabetes are age-specific. METHODS: We conducted a retrospective analysis of a territory-wide diabetes surveillance dataset from the Hong Kong Hospital Authority between 2000 and 2019. Prediabetes was defined according to the American Diabetes Association criteria. Proportional Cox regression was performed, stratified by baseline age categories (20-39, 40-59, 60-79 and ≥80 years). FINDINGS: 1,630,942 individuals were included in the analysis. Compared with normoglycaemia, prediabetes was associated with greater hazards for cardiovascular disease (CVD) and all-cause mortality in most age groups but the effect size attenuated with ascending age (p value for trend <0·05). In the youngest and in the oldest age categories, the respective hazard ratios (95% confidence interval) of prediabetes vs normoglycaemia were 1·79 (1·59, 2·01) and 1·00 (0·95, 1·05) for CVD, and 1·36 (1·20, 1·55) and 0·99 (0·97, 1·02) for all-cause mortality. Similar associations were found for chronic kidney disease, end-stage kidney disease, all-site cancer, all-site infection, subtypes of CVD, and cause-specific mortality. The associations became attenuated but remained after excluding people who later developed diabetes and adjusting for metabolic factors. Similar associations were observed in prediabetes defined by impaired fasting glucose, but not HbA1c. INTERPRETATION: Prediabetes is associated with higher risk of major clinical events, even excluding subsequent development of diabetes and adjusting for metabolic factors. The risk relationships are stronger in young than older people. FUNDING: This study did not receive any specific funding.