Are antihypertensive drugs associated with an increased risk of incident type 2 diabetes?

Background It has been suggested that some classes of antihypertensive drugs might be associated with an increased risk of type 2 diabetes. Objective To evaluate the effect of thiazide diuretics, beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, and calcium-channel blockers (CCBs) on the incidence of type 2 diabetes. Design and Intervention This was a prospective study of three cohorts of health-care professionals: the Nurses Health Study (NHS) I, NHS II, and the Health Professionals Follow-up Study (HPFS). Prospective participants completed a questionnaire to assess lifestyle and medical history. Participants with a history of diabetes were excluded. Biennial questionnaires were used to evaluate any changes from baseline, and included data on newly diagnosed diseases, history of hypertension, and medication (including use of anti hypertensive drugs). Participants who reported a diagnosis of diabetes were sent a supplementary questionnaire to record their symptoms, hypoglycemic medication, and diagnostic tests. A reported case of diabetes was considered confirmed if at least one of the following criteria was met: one or more typical symptoms of diabetes plus a fasting blood glucose level of >= 7.8 mmol/l (before 1996) or >= 7.0 mmol/l (after 1996), at least two elevated plasma glucose level measurements after a glucose tolerance test in the absence of Are antihypertensive drugs associated with an increased risk of incident type 2 diabetes? symptoms, and treatment with insulin or oral antidiabetic medications. Outcome Measure The primary outcome measure was the incidence of newly diagnosed type 2 diabetes. Results The NHS I cohort comprised 41,193 women (aged 30-55 years at enrollment); the NHS II cohort comprised 14,151 women (aged 25-42 years at enrollment); and the HPFS cohort comprised 19,472 men (aged 40-75 years at enrollment). Type 2 diabetes was confirmed in 2,069 NHS I participants, 426 NHS II participants, and 1,094 HPFS participants. All participants reported a history of hypertension. Use of thiazide diuretics was independently associated with an increased risk of symptomatic type 2 diabetes in all three cohorts: multivariate relative risk (RR) of symptomatic disease 1.20, 1.51, and 1.31 for NHS I, NHS II, and HPFS, respectively. The multivariate RR for combined symptomatic and asymptomatic disease in participants taking thiazide diuretics was 1.20, 1.45, and 1.36 for NHS I, NHS II, and HPFS, respectively. Use of beta-blockers was associated with an increased risk of type 2 diabetes in NHS I and HPFS participants. The multivariate RR of symptomatic disease in participants taking beta-blockers was 1.25 for NHS I and 1.21 for HPFS, whereas the multivariate RR for combined symptomatic and asymptomatic disease was 1.32 and 1.20 for NHS I and HPFS, respectively. Use of ACE inhibitors and CCBs was not associated with an increased risk of symptomatic type 2 diabetes. Conclusion Use of thiazide diuretics and beta-blockers was associated with an increased risk of type 2 diabetes, which suggests that patients treated with these drugs might benefit from routine blood glucose monitoring.