Serum lipoproteins and indices of glucose tolerance during diuretic therapy: a comparison between hydrochlorothiazide and piretanide.

Two diuretic drugs, hydrochlorothiazide (HCT) and piretanide (PT), were compared for their effects on plasma lipoproteins and glucose tolerance in 24 hypertensive male subjects over a period of 12 weeks. In comparison with preceding placebos, both drugs caused an increase of total cholesterol, low-density lipoprotein (LDL) cholesterol, total triglyceride, and very-low-density lipoprotein (VLDL) triglyceride concentrations, whereas no significant change occurred in high-density lipoprotein (HDL) cholesterol. The alterations were partly reversible in patients receiving HCT. Apoprotein A and B concentrations were increased by PT but were little influenced by HCT. Also, the LDL/HDL cholesterol ratio was increased during PT. Neither drug invariably influenced the postheparin plasma lipase activities, oral glucose tolerance, plasma insulin levels, or insulin binding to red cells. The results suggest that diuretic drugs may promote the hepatic secretion of VLDL. The mechanism of this action remains to be established, and the clinical relevance of these findings is still not clearly understood.