Antihypertensive drugs as predictors of Type 2 diabetes among subjects with impaired glucose tolerance

Aims: to examine the incidence rate of progression to Type 2 diabetes and b aseline prognostic risk factors, focusing on hypertension and antihypertens ive medication, in a cohort (n = 207) with impaired glucose tolerance (IGT) . Methods: after 2 and 4.6 (1.9-6.4) years new cases of diabetes were diagn osed by the oral glucose tolerance test (OGTT). Hypertension (BP 160/95 or antihypertensive medication) was included in multiple regression analyses t o assess the effect of risk factors on the development of diabetes. Results : diabetes developed in 32 subjects (19%), an incidence of 41/1000 (95% CI 28-57/1000) person-years. In univariate analyses, progression to diabetes w as associated with a high (> 9.0 mmol/l) 2-h OGTT value (P = 0.008), a high fasting insulin (> 12.0 mU/l) level (P=0.000), a high triglyceride (greate r than or equal to1.3 mmol/l) level (P=0.028), a high BMI (228.0 kg/m(2)) ( P=0.013) and hypertension (P = 0.003). The risk for the development of diab etes was not increased in hypertensive subjects without antihypertensive me dication compared with normotensive subjects (OR 0.8, 95% CI 0.3-2.6). Howe ver, it was increased in subjects with on medication, especially diuretics alone or in combination with other drugs. Hypertensive subjects on diuretic s had higher levels of fasting insulin and triglycerides and higher BMIs at baseline than normotensive subjects. After adjustment for 2-h OGTT, fastin g insulin, triglycerides and BMI, the OR for diabetes was 7.7 (95% CI 2.1-2 8.2) in hypertensive subjects using diuretics alone or in combination with other drugs and 2.6 (95% CI 1.0-6.7) in those using other drugs compared wi th normotensive subjects. The OR of diabetes corresponding to a one-unit in crease in the 2-h OGTT concentration was 2.5 (95% CI 1.6-4.0) in the whole cohort. Conclusions: the rate of progression from IGT to Type 2 diabetes in this population was similar to that seen in other studies among Caucasian populations. The use of antihypertensive medication, especially diuretics, and a high 2-h OGTT level were significant predictors of subsequent deterio ration to diabetes. (C) 2000 Elsevier Science Ireland Ltd. All rights reser ved.