Glycemic Measures and Risk of Mortality in Older Chinese: The Guangzhou Biobank Cohort Study

Abstract

Abstract Context China has the largest number of people with type 2 diabetes mellitus (T2DM) in the world. Data from previous studies have suggested that up to one-fifth of individuals with diabetes would be missed without an oral glucose tolerance test (OGTT). To date, there is little information on the mortality risk of these individuals. Objective We estimated the association of different indicators of hyperglycemia with mortality in the general Chinese population. Design Prospective cohort study. Setting China. Participants A total of 17 939 participants aged 50+ years. Exposures Previously diagnosed diabetes and newly detected diabetes defined by fasting glucose (≥7.0 mmol/L), 2-hour postload glucose (≥11.1 mmol/L), or hemoglobin A1c (HbA1c, ≥6.5%). Main Outcomes Measures Deaths from all-cause, cardiovascular disease, and cancer were identified by record linkage with death registration. Results During 7.8 (SD, 1.5) years’ follow-up, 1439 deaths were recorded. Of 3706 participants with T2DM, 2126 (57%) had known T2DM, 118 (3%) were identified by isolated elevated fasting glucose, 1022 (28%) had isolated elevated postload glucose, and 440 (12%) had both elevated fasting and postload glucose. Compared with normoglycemia, the hazard ratio (95% confidence interval) of all-cause mortality was 1.71 (1.46-2.00), 0.96 (0.47-1.93), 1.43 (1.15-1.78), and 1.82 (1.35-2.45) for the 4 groups, respectively. T2DM defined by elevated HbA1c was not significantly associated with all-cause mortality (hazard ratio, 1.17; 95% confidence interval, 0.81-1.69). Conclusion Individuals with isolated higher 2-h postload glucose had a higher risk of mortality by 43% than those with normoglycemia. Underuse of OGTT leads to substantial underdetection of individuals with a higher mortality risk and lost opportunities for early intervention.