Antihypertensive medications and risk of diabetes mellitus

Type 2 Diabetes and Thiazide Diuretics

PURPOSE OF REVIEW

In patients with prediabetes or type 2 diabetes, the use of thiazides as antihypertensive agents has been challenged because associated metabolic adverse events, including new-onset diabetes.

RECENT FINDINGS

These metabolic disturbances are less marked with low-dose thiazides and, in most but not all studies, with thiazide-like diuretics (chlorthalidone, indapamide) than with thiazide-type diuretics (hydrochlorothiazide). In post hoc analyses of subgroups of patients with hypertension and type 2 diabetes, thiazides resulted in a significant reduction in cardiovascular events, all-cause mortality, and hospitalization for heart failure compared to placebo and generally were shown to be non-inferior to other antihypertensive agents. Benefits attributed to thiazide diuretics in terms of cardiovascular event reduction outweigh the risk of worsening glucose control in type 2 diabetes and of new-onset diabetes in non-diabetic patients. Thiazides still play a key role in the management of patients with type 2 diabetes and hypertension.

Metabolic complications associated with use of diuretics

Diuretics are commonly used therapeutic agents that act to inhibit sodium transport systems along the length of the renal tubule. The most effective diuretics are inhibitors of sodium chloride transport in the thick ascending limb of Henle. Loop diuretics mobilize large amounts of sodium chloride and water and produce a copious diuresis with a sharp reduction of extracellular fluid volume. As the site of action of diuretics moves downstream (thiazide and potassium-sparing diuretics), their effectiveness declines because the transport systems they inhibit have low transport capacity. Depending on the site of action diuretics can influence the renal handling of electrolyte-free water, calcium, potassium, protons, sodium bicarbonate, and uric acid. As a result, electrolyte and acid-base disorders commonly accompany diuretic use. Glucose and lipid abnormalities also can occur, particularly with the use of thiazide diuretics. This review focuses on the biochemical complications associated with the use of diuretics. The development of these complications can be minimized with careful monitoring, dosage adjustment, and replacement of electrolyte losses.

Long-term effects of incident diabetes mellitus on cardiovascular outcomes in people treated for hypertension: the ALLHAT Diabetes Extension Study

BACKGROUND

Thiazide-type diuretics are associated with an increased incidence of diabetes compared with other antihypertensive medications. In this study, we determined the long-term cardiovascular disease (CVD) consequences of incident diuretic-associated diabetes compared with the effects of incident diabetes associated with calcium channel blocker and angiotensin-converting enzyme inhibitor use.

METHODS AND RESULTS

A total of 22 418 participants from the ALLHAT (Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial) with baseline diabetes, incident diabetes (7.5% with chlorthalidone, 5.6% with amlodipine, and 4.3% with lisinopril), or no diabetes at 2 years of in-trial follow-up were followed for a mean total of 6.9 years (2.9 years in-trial and 4 additional years posttrial) through the use of national databases. The primary outcome was CVD mortality (death from coronary heart disease [CHD], stroke, heart failure, or other CVD). Among other outcomes were all-cause mortality, non-CVD mortality, and CHD (nonfatal myocardial infarction or fatal CHD). Participants on chlorthalidone with incident diabetes versus no diabetes had consistently lower, nonsignificant risk for CVD mortality (hazard ratio [HR], 1.04; 95% CI, 0.74-1.47), all-cause mortality (HR, 1.04; 95% CI, 0.82-1.30), and non-CVD mortality (HR, 1.05; 95% CI, 0.77-1.42) than participants on amlodipine or lisinopril with incident diabetes (HR range, 1.22-1.53). Participants with incident diabetes had elevated CHD risk compared with those with no diabetes (HR, 1.46; 95% CI, 1.09-1.96), but those on chlorthalidone had significantly lower risk than those on lisinopril (HR, 1.18 versus 2.57; P=0.04 for interaction).

CONCLUSIONS

The findings suggest that thiazide-related incident diabetes has less adverse long-term CVD impact than incident diabetes that develops while on other antihypertensive medications.

Improving BP control with combined renin-angiotensin system blockade and thiazide diuretics in hypertensive patients with diabetes mellitus or kidney disease

Most hypertensive patients will require more than one antihypertensive drug to lower BP below target levels. The combination of diuretics with renin-angiotensin system (RAS) antagonists offers several advantages to include additive BP-lowering efficacy and enhanced reductions in urinary protein excretion. Thiazide diuretics are associated with metabolic complications that are particularly evident when used in high doses. When used in combination with RAS blockade, metabolic complications such as hypokalemia are minimized. The avoidance of hypokalemia has been linked to less thiazide-induced glucose intolerance. Patient persistence on therapy is dependent on well tolerated drug combinations.