Objective: The objective of this study was to analyse predictive factors for development of type 2 diabetes during life-long therapy for hypertension and the alleged additional cardiovascular risk this constitutes.
Methods: The study group (n = 754) comprised the hypertensive subgroup of a randomized population sample of 7500 men, aged 47-54 years, screened for cardiovascular risk factors and followed for 25-28 years. The patients were treated with thiazide diuretics and beta-adrenergic blocking drugs with the addition of hydralazin during the first decade. Calcium antagonists were substituted for hydralazin and, if needed, angiotensin-converting enzyme inhibitors were added when these drugs became available.
Results: A total of 148 (20.4%) treated hypertensive patients developed diabetes during 25 years, and in multivariate Cox regression analysis body mass index, serum triglycerides and treatment with beta-blockers were positively related with this complication. New-onset diabetes implied a significantly increased risk for stroke [hazard ratio (HR): 1.67; 95% confidence interval (95% CI): 1.1-2.6; P < 0.05], myocardial infarction (OR: 1.66; 95% CI: 1.1-2.5; P < 0.05) and mortality (OR: 1.42; 95% CI: 1.1-1.9; P < 0.05). The greatest risk for stroke was new-onset diabetes, followed by smoking (OR: 1.46; 95% CI: 1-2.2; P = 0.07) and the greatest risk for myocardial infarction was new-onset diabetes, followed by smoking (HR: 1.64; 95% CI: 1.1-2.4; P < 0.01). The greatest risk for mortality was smoking (HR: 1.73; 95% CI: 1.3-2.2; P < 0.005). Achieved systolic and diastolic blood pressure were not predictive of cardiovascular complications or death. The mean observation time from onset of diabetes mellitus to a first stroke was 9.1 years and to a first myocardial infarction 9.3 years.
Conclusion: Diabetes in treated hypertensive patients is alarmingly common and carries a high risk for cardiovascular complications and mortality.