What effect do thiazide diuretics have on glucose metabolism?

Thiazide diuretics are known to potentially impair glucose tolerance due to their mechanism of action and the physiological changes they induce. These medications can lead to increased levels of glucose in the blood by promoting insulin resistance, which is particularly relevant in patients predisposed to diabetes or prediabetes. The diuretic's actions can lead to alterations in electrolyte balance, most notably with hypokalemia (low potassium levels), which can further impact insulin secretion and sensitivity.

Over time, this impairment in glucose metabolism can result in increased fasting blood glucose levels and a higher risk of developing type 2 diabetes, particularly in individuals who are already at risk. Therefore, when considering the impact of thiazide diuretics on glucose metabolism, the most accurate assessment is that they may impair glucose tolerance, which aligns with the provided answer.