Postchallenge Hyperglycemia and Mortality in a National Sample of U.S. Adults

Abstract

OBJECTIVE—Although postchallenge hyperglycemia is a well-established feature of type 2 diabetes, its association with risk of mortality is uncertain. Therefore, the aim of this study was to assess the independent association of fasting and 2-h glucose levels with all-cause and cardiovascular disease (CVD) mortality.

RESEARCH DESIGN AND METHODS—We analyzed data from the Second National Health and Nutrition Examination Survey (NHANES II) Mortality Study, a prospective cohort study of U.S. adults examined in the NHANES II, and focused on the 3,092 adults aged 30–74 years who underwent an oral glucose tolerance test at baseline (1976–1980). Deaths were identified from U.S. national mortality files from 1976 to 1992. To account for the complex survey design, we used SUDAAN statistical software for weighted analysis.

RESULTS—Compared with their normoglycemic counterparts (fasting glucose [FG] <7.0 and 2-h glucose <7.8 mmol/l), adults with fasting and postchallenge hyperglycemia (FG ≥7.0 and 2-h glucose ≥11.1 mmol/l) had a twofold higher risk of death after 16 years of follow-up (age- and sex-adjusted relative hazard [RH] 2.1, 95% CI 1.4–3.2). However, adults with isolated postchallenge hyperglycemia (FG <7.0 and 2-h glucose ≥11.1 mmol/l) were also at higher risk of death (1.6, 1.0–2.6). In proportional hazards analysis, FG (fully adjusted RH 1.10 per 1 SD; 95% CI 1.01, 1.22) and 2-h glucose (1.14, 1.00–1.29) showed nearly identical predictive value for mortality. Similar trends were observed for CVD mortality.

CONCLUSIONS—These results suggest that postchallenge hyperglycemia is associated with increased risk of all-cause and CVD mortality independently of other CVD risk factors.