Hypertension in diet versus pharmacologically treated diabetics: mortality over a 5-year follow-up

Abstract

The natural history of non-insulin-dependent diabetes mellitus (NIDDM) differs markedly between patients with diet treated and pharmacologically treated disease. However, the interrelationship between hypertension and these common diabetes types has not been specifically addressed in previous studies. This study was designed to evaluate the prognostic significance and prevalence of hypertension in coronary patients with diet versus pharmacologically treated NIDDM over a 5-year follow-up period. The study sample comprised 11 515 patients aged 45 to 74 years with a previous myocardial infarction and/or anginal syndrome who had been screened but were not included in the Bezafibrate Infarction Prevention study. Among them, 9033 were nondiabetics and 2482, diabetics (987 diet treated and 1495 pharmacologically treated). The prevalence of hypertension among nondiabetics, diet-treated diabetics, and pharmacologically treated diabetics was 31%, 42%, and 43%, respectively. Crude all-cause mortality (CM) was lower in the nondiabetic patients (11.2% versus 22.0%; P<0.001). Among diabetics, 548 patients died: 81 diet treated normotensives (CM 14%); 100 diet-treated hypertensives (CM 24.4%); 205 pharmacologically treated normotensives (CM 24.2%); and 162 pharmacologically treated hypertensive patients (CM 25.0%). Age-adjusted mortality was lowest for the normotensive patients in the diet-treated group and highest for the hypertensive pharmacologically treated patients. Multivariate analysis shows that hypertension is a strong and independent predictor of increased CM in diet-treated but not in pharmacologically treated NIDDM: hazard ratio (HR) was 1.68 (95% confidence interval [CI] 1.24 to 2.29) for the diet-treated versus 1. 01 (95% CI 0.82 to 1.26) for the pharmacologically treated diabetics. The contribution of hypertension to stroke mortality was substantial for both diet treated and pharmacologically treated NIDDM: hazard ratios were 3.17 (95% CI 1.12 to 8.98) and 2.21 (95% CI 0.72 to 6.77), respectively. The increased risk of mortality associated with hypertension in relatively mild diet-treated NIDDM strongly supports the clinical benefit of early blood pressure control among diabetic patients with ischemic heart disease.