What is the connection between thiazide diuretics and diabetes?

Anthony L. Komaroff, MD
Internal Medicine
The Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) is probably the most influential study of blood pressure medication ever conducted. It included 33,000 people who were randomized to take one of three blood pressure-lowering medications: a thiazide diuretic, a calcium-channel blocker, or an ACE inhibitor. The rate of heart attacks and deaths from heart disease was similar in all three groups, but the thiazide group had a lower rate of heart failure.

Researchers analyzed the ALLHAT data to see how the three different medications affected blood sugar levels. They found that all three were associated with an increase in blood sugar, but more people in the thiazide group (11.6%) were diagnosed with diabetes than those assigned to take the calcium-channel blocker (9.8%) or the ACE inhibitor (8.1%). This modest difference in the risk for developing diabetes did not, however, translate into more heart attacks or other problems. So, on balance, the benefits of thiazide diuretics -- controlling and preventing hypertension-associated events -- outweigh the risk of developing diabetes.

I think the thiazide diuretics remain an excellent first choice for most people with high blood pressure, and the small increased risk of developing diabetes seen in the ALLHAT study shouldn't deter patients from taking them or physicians from prescribing them.

Continue Learning about Diabetes


Diabetes mellitus (MEL-ih-tus), often referred to as diabetes, is characterized by high blood glucose (sugar) levels that result from the body’s inability to produce enough insulin and/or effectively utilize the insulin. Diabetes ...

is a serious, life-long condition and the sixth leading cause of death in the United States. Diabetes is a disorder of metabolism (the body's way of digesting food and converting it into energy). There are three forms of diabetes. Type 1 diabetes is an autoimmune disease that accounts for five- to 10-percent of all diagnosed cases of diabetes. Type 2 diabetes may account for 90- to 95-percent of all diagnosed cases. The third type of diabetes occurs in pregnancy and is referred to as gestational diabetes. Left untreated, gestational diabetes can cause health issues for pregnant women and their babies. People with diabetes can take preventive steps to control this disease and decrease the risk of further complications.

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