Thiazide and Beta-Blocker Use Linked With Increased Risk for Diabetes

In 3 large cohort studies it was found that thiazide diuretics and beta-blockers appear to be associated with an increased relative risk for incident diabetes. By contrast, angiotensin-converting enzyme (ACE) inhibitors and calcium channel blockers were not associated with an increased risk.

Eric N. Taylor, MD, with the Brigham and Women’s Hospital, and Harvard Medical School, in Boston, Mass, stated that, “Our study suggests that individuals treated with these medications merit increased surveillance for diabetes.”

Dr Taylor and colleagues conducted a prospective study of participants from the Nurses’ Health Study (NHS) I, the NHS II, and the Health Professionals Follow-up Study (HPFS). Participants were questioned about their use of antihypertensives once every 2 years. All subjects had hypertension (systolic and diastolic blood pressures greater than 140 and 90 mm Hg, respectively), but those reporting a history of diabetes at baseline were excluded from the analysis.

The NHS I included 41 193 older women (aged between 30 and 55 years in 1976); the NHS II included 14 151 younger women (aged between 25 and 42 years in 1989); and the HPFS included 19 472 men (aged between 40 and 75 years in 1986). Participants were followed up for 8, 10, and 16 years, respectively.

During follow-up, 3589 cases of diabetes developed. Results were adjusted for several risk factors, including, age, body mass index, physical activity, and the use of other antihypertensive medications.

After adjustment, the relative risk of incident diabetes for those taking a thiazide diuretic compared with those not taking a thiazide was 1.20 (95% confidence interval [CI], 1.08 – 1.33) in older women; 1.45 (95% CI, 1.17 – 1.79) in younger women; and 1.36 (95% CI, 1.17 – 1.58) in men.

Likewise, the risk for incident diabetes was also increased in patients taking beta-blockers relative to those who were not: 1.32 (95% CI, 1.20 – 1.46) in older women and 1.20 (95% CI, 1.05 -1.38) in men. In younger women, a category of “other antihypertensives” was used that included beta-blockers, and their use was associated with an increased risk for 1.46 (95% CI, 1.19 – 1.80).

By contrast, no increase in risk was associated with taking ACE inhibitors or calcium-channel blockers.

According to the researchers, emerging evidence suggests that therapy with ACE inhibitors and angiotensin-receptor blockers, may, in fact, decrease the risk for incident diabetes. They also cited several previous studies indicating mixed results with regard to beta-blockers and diabetes risk.

Pearls for Practice
· In the ALLHAT study, chlorthalidone increased the risk for incident type 2 diabetes to a greater degree than amlodipine or lisinopril.
· In the current study, thiazide diuretics and beta-blockers increased the risk of developing type 2 diabetes in men and women.
Diabetes Care. 2006;29:1065-1070