Effect of reduction of plasma triglycerides with gemfibrozil on high‐density‐lipoprotein‐cholesterol concentrations

Abstract. The aim of this study was to test the hypothesis that the plasma triglyceride (TG) concentration must be reduced below approximately 0.85‐1.13 mmol l^‐1 (75–100 mg/dl^‐1) in order to achieve a substantial increase in plasma high‐density‐lipoprotein‐cholesterol (HDL‐C) levels. The study design consisted of a non‐randomized clinical trial, which was conducted at an out‐patient clinic at a university‐affiliated VA Medical Center. The participants consisted of 55 ambulatory middle‐aged men with a baseline fasting HDL‐C concentration of < 1.17 mmol l^‐1 (45 mg dl^‐1) and baseline TG in the range 1.13‐5.6 mmol l^‐1 (100–500 mg dl^‐1). Subjects were treated with gemfibrozil, 600 mg twice a day for 3 months. Fasting plasma HDL‐C, TG, low density lipoprotein‐cholesterol, and total cholesterol were measured at 1‐month intervals for 3 months. Subjects were divided into three groups on the basis of TG level achieved on therapy: Group 1 (n = 14), TG < 0.85 mmol l^‐1 (75 mg dl^‐1); Group II (n = 20), TG 0.86‐1.41 mmol l^‐1 (76–125 mg dl^‐1); Group III (n = 21), TG > 1.41 mmol l^‐1 (125 mg dl^‐1). The mean increase in HDL‐C in Group I was 0.20 mmol l^‐1 (7.8 mg dl^‐1), a significantly (P = 0.0067) greater increase than was observed in the other two groups. There was no correlation between the magnitude of change in TG and the magnitude of change in HDL‐C concentration in the group as a whole (Pearson'n correlation coefficient, r = ‐0.06. P = 0.6). In conclusion, the increase in HDL‐C levels observed with gemfibrozil therapy is associated with the absolute level of TG achieved by therapy. Substantial increases in HDL‐C concentration might not be expected to occur consistently unless TG levels are reduced to values that are considered below the usually cited ‘normal’ range. 1992 Blackwell Publishing Ltd