Effects of diabetes and level of glycemia on all-cause and cardiovascular mortality. The San Antonio Heart Study.

OBJECTIVE: Although the level of hyperglycemia is clearly a risk factor for microvascular complications in diabetic patients, its role in macrovascular complications remains controversial. We followed 4,875 subjects (65% Mexican-American) for 7-8 years to investigate the effects of diabetes and hyperglycemia on all-cause and cardiovascular disease (CVD) mortality. These end points were also analyzed according to quartiles of baseline fasting plasma glucose among diabetic participants.

RESEARCH DESIGN AND METHODS: The Cox proportional hazards model was used to estimate the relative risks (RRs) for all-cause and CVD mortality.

RESULTS: Diabetes was significantly associated with increased all-cause mortality (RR [95% CI] = 2.1 [1.3-3.5] in men; 3.2 [1.9-5.4] in women) and increased CVD mortality (3.2 [1.4-7.1] in men; 8.5 [2.8-25.2] in women). Among diabetic subjects, those in quartile 4 had a 4.2-fold greater risk of all-cause mortality (P < 0.001) and a 4.7-fold greater risk of CVD mortality (P = 0.01) than those in quartiles 1 and 2 combined. After further adjustment for other potential risk factors, subjects in quartile 4 had a 4.9-fold greater risk of all-cause mortality and a 4.9-fold greater risk of CVD mortality than those in quartiles 1 and 2. In addition, hypertension, current smoking, and cholesterol > 6.2 mmol/l were significant predictors of CVD mortality using Cox models.

CONCLUSIONS: We conclude that diabetes is a predictor of both all-cause and CVD mortality in the general population and that both hyperglycemia and common CVD risk factors are important predictors of all-cause and CVD mortality in diabetic subjects.