Influence of West African Ethnicity and Gender on Beta-Cell Function and Insulin Sensitivity in Essential Hypertensives Treated with Hydrochlorothiazide and Hydrochlorothiazide-lisinopril Combination.

OBJECTIVE

To assess the effects of hydrochlorothiazide (HCT) given alone and in combination with an angiotensin-converting enzyme inhibitor (ACEI) on beta-cell function in a negroid population to further explore possible ethnic differences in the effect of antihypertensive drugs on homeostasis model assessment - insulin resistance (HOMA-IR).

MATERIALS AND METHODS

A total of 80 newly diagnosed Nigerian essential hypertensive patients were assigned to receive either HCT 25 mg daily or both HCT and lisinopril (Lis; 25/10 mg daily) in an open-label study for 12 weeks. The treatment groups were well matched in clinical and demographic baseline features. Changes in HOMA-IR from baseline to end of study (week 12), fasting plasma glucose (FPG), serum potassium, serum insulin, and blood pressure over the same period were also evaluated.

RESULTS

After 12 weeks, mean delta HOMA-IR (and %) was higher in the HCT monotherapy group; although, this change did not reach statistical significance in both groups -0.1 ± 7.1, = 0.538 (HCT) and 0.6 ± 4.2 = 0.913 (HCT + Lis); an insignificant increase was observed in FPG and serum insulin in both groups, whereas serum potassium decreased in similar fashion. Blood pressure reduction was similar in both groups. Analysis of HOMA-IR change according to gender in response to HCT mono- or combination therapy with Lis showed no significant difference.

CONCLUSIONS

HCT monotherapy in hypertensive indigenous Nigerians, was not associated with worse metabolic effects when compared with combination therapy using Lis, an ACEI after 12 weeks. Low-dose thiazide diuretic as first-line antihypertensive medication may be safe in the short-term, further larger and long-term studies are needed to corroborate this finding.