Doxazosin,but not amlodipine decreases insulin resistance in patients with chronic renal failure: a prospective,randomized-controlled study

Insulin resistance (IR) in chronic renal failure (CRF) is well-known. In this randomized-controlled study, we aimed to compare the effect of doxazosin and amlodipine on IR in patients with CRF. Fifteen patients with CRF (male/female: 5/10, mean age: 46 +/- 13 years) and 9 controls (male/female: 3/6, mean age: 35 +/- 8 years) were included. Patients and controls had no family history of diabetes mellitus. Homeostasis model assessment (HOMA) was calculated as a marker of IR. Patients were grouped randomly to doxazosin (n = 8; 2-4 mg/day) and amlodipine (n = 7; 5-10 mg/day) arms. Baseline biochemical analysis (fasting serum glucose, BUN, creatinine, uric acid, cholesterol and cholesterol subgroups) and parameters related with insulin metabolism (insulin, C peptide, HOMA) were similar between amlodipine and doxazosin groups. There was no difference in age, gender and body mass index among study groups. The follow-up time was 12 weeks. Patients with CRF had higher HOMA (1.83 +/- 0.55 vs 1.00 +/- 0.36, p = 0.001), fasting insulin (8.06 +/- 1.98 vs 4.46 +/- 1.31 IU/l, p < 0.001) and serum triglyceride levels (197 +/- 136 vs 112 +/- 67 mg/dl, p = 0.04) as compared to controls. Serum HDL cholesterol levels were significantly lower in patients with CRF than controls (40 +/- 10 vs 57 +/- 14 mg/dl, p = 0.02). HOMA significantly decreased after doxazosin (1.91 +/- 0.45 vs 1.41 +/- 0.21, p = 0.02), however, no difference was found after amlodipine. Also, fasting insulin levels were decreased after a 12-week doxazosin therapy from 8.17 +/- 1.22 vs 6.58 +/- 0.84 IU/l, p = 0.02), but no change was seen after amlodipine. Lipid parameters did not significantly change during the study period in 2 groups. No adverse effect requiring drug discontinuation was observed during the 12-week period in the study groups. In conclusion, doxazosin decreases IR in patients with CRF, whereas amlodipine has no effect. This may be of advantage in the treatment of hypertension in this group of patients for preventing some long-term complication of IR.