2. Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, Canada.
Background: Antihypertensive drugs including thiazide diuretics, beta blockers (BB), calcium channel blockers (CCB), reninangiotensin inhibitors or vasodilators produce elevated blood glucose (hyperglycemia) (>70-99 mg/dL). Hyperglycemia is more common and severe with thiazide diuretics than with BB, CCB, ACEI or ARB drugs. Questions have been raised about the mechanism and risk of drug-induced hyperglycemia.
Method: We present here four patients treated with diuretics who developed hyperglycemia - fasting blood glucose (FBG) > 126 mg/ dL (7 mmol/L) diagnostic of diabetes. Three patients had hypertension and one, congestive heart failure (CHF). Three patients had no diabetes, one gave 8 to 10 year history of diabetes. One patient received no diuretic therapy and his glucose level was normal with insulin and oral hypoglycemic agent treatment. Subsequently, he became hypertensive and was treated with a thiazide diuretic but no antidiabetic agents. He then developed new-onset diabetes.
Results: All patients showed hyperglycemia above FBG criteria for diabetes. 2-hour postprandial blood glucose (2hPPG) was not diagnostic of diabetes in three patients. Two patients were prescribed antidiabetic therapy which was stopped with no worsening of hyperglycemia although diuretic therapy continued. In two patients diuretic was discontinued. Hyperglycemia abated in one, while in the other, hyperglycemia worsened requiring Glargine insulin.
Conclusion: Hyperglycemia is common in patients with hypertension or CHF treated with a thiazide diuretic alone or in combination with other diuretics. Although by definition the term new-onset diabetes may be used to connote hyperglycemia, in reality diabetes induced by diuretics is not diabetes as 2hPPG does not usually exceed 200 mg/dL (11.1 mmol/L), and patients show no evidence of any vascular complications. It may be more appropriate to define elevated glucose associated with diuretic "hyperglycemia" rather than new-onset diabetes. The real issue is that use of thiazide diuretics is imperative in blood pressure control especially in resistant hypertension. Even with new-onset diabetes, thiazide diuretics are commonly found to be safe, reducing risk of stroke, heart attack, and renal failure characteristic of uncontrolled hypertension. Therefore, risks of new-onset diabetes, induced by diuretic therapy, will be difficult to ascertain because of hypertension for which thiazide diuretic is widely used.
keywords: hyperglycemia, diuretics, diabetes