I was asked about the clinical of thiazides and hyperglycemia. To be honest, studies aren’t that great surrounding this question, and the main ones I’m aware of and could find were very old. Here’s a quick breakdown of a couple of studies on the risk of thiazides contributing to hyperglycemia.
The original study that was done that I am aware of is from 1977…yes, over 40 years old. Needless to say, we do things a little differently nowadays. Here’s the abstract;
“A 20% or greater rise in the fasting blood sugar occurred in 11 of 24 patients treated with 50 mg hydrochlorothiazide twice daily for six to ten weeks. The blood sugar decreased when potassium was given in conjunction with the diuretic, but the mean fasting blood sugar remained higher than pretreatment levels.”
How many times in clinical practice have I seen 50 mg twice daily? Not many. To be honest, I can’t remember it if I have ever seen it.
The other article I found on the topic of thiazides and hyperglycemia is much newer, but still very old in the grand scheme of things. This one was from 1997. Here’s a segment of the abstract that discusses hyperglycemia risk.
“Fasting plasma glucose and hemoglobin A1 increased significantly (p < 0.05) only in group A (combination of hydrochlorothiazide 33 mg/day and sotalol) after 1 year of treatment (from 91.6 to 98.0 mg/dl, and from 6.3 to 6.9%, respectively). Our data show that the diuretic/beta-blocker combination has adverse effects on lipid and glucose metabolism after long-term therapy. The effects of the diuretic/ACE inhibitor combination on lipid metabolism are less pronounced and there are no adverse effects on glucose metabolism. However, the ACE inhibitor component could not completely counteract the metabolic effects of the diuretic.”
In this article, hydrochlorothiazide was used in combination with an ACE inhibitor in one group and sotalol in the other group. The sotalol/HCTZ group had a significant increase in blood sugar. The ACE/HCTZ group did not. This is another situation where we can pick gigantic holes in this data. For one, when is sotalol or captopril ever used in hypertension? Virtually never.
Bottom Line – Thiazides and Hyperglycemia
I typically don’t worry too much about the risk of thiazides and hyperglycemia, and this is especially true in patients taking low dosages of thiazides. If you have a patient taking higher dosages as the first article had, I may get a little more concerned about it. With that said, if I have a patient who reports elevated blood sugars and doesn’t have a reason as to why they have gone up, I do include thiazides in my medication-related differential.