FACTORS INFLUENCING THRESHOLD AND CHOICE OF TREATMENT FOR HYPERTENSION IN NIDDM - CARDIOVASCULAR FACTORS

In nondiabetic populations, there is an approximately 40% increase in stroke risk and a 25% increase in coronary heart disease (CHD) risk with every 6-mmHg increase above 75 mmHg in usual diastolic blood pressure. Diabetes increases the risk of both conditions by two- to threefold, and in diabetic patients, hypertension further increases these risks. The benefits of lowering blood pressure in nondiabetic subjects have been subjected to meta-analysis, which has demonstrated benefits equivalent to 100% reversal of the excess risk for stroke but with only approximately 50% of CHD risk reversible after 2-3 yr of treatment. In these analyses, the benefit of treating diastolic blood pressure is similar at all levels > 90 mmHg. If these results are extrapolated to diabetic patients, possible benefits of therapy for mild hypertension could be two to three times greater than in nondiabetic subjects, but this could still correspond to 300 person-yr of treatment to prevent one nonfatal stroke and 2500 person-yr of treatment to prevent one CHD death, with treatment that may deleteriously affect quality of life in 36% of all diabetic patients. There may also be risks in treating patients with mild hypertension who have existing CHD or left ventricular hypertrophy, which are more common in diabetes. Despite the theoretical risk of deleterious changes in several cardiovascular risk factors with thiazides or beta-blockers, most of the newer agents have not yet been demonstrated to produce similar benefits to the large prospective studies in which the aforementioned agents have been used. It is only with prospective studies in high-risk diabetic populations that the treatments can be compared and the possible risks of a J-shaped curve assessed.