Objective PPARγ agonists are widely used in type 2 diabetic patients to reduce insulin resistance. Recently, telmisartan, an AT1 receptor antagonist, was reported to function as a partial agonist of PPARγ based on in vitro experiments. The aim of the present study was to investigate whether the PPARγ enhancing activity of telmisartan is exerted clinically in diabetic patients.
Methods We compared the effects of telmisartan with those of candesartan, on insulin sensitivity, the serum levels of various adipocytokines and oxidative stress.
Patients In total, 85 Japanese type 2 diabetic patients with hypertension, maintained on 8 mg per day of candesartan, were randomly assigned to the TM group (candesartan switched to 40 mg of telmisartan, n=38) or the CD group (no treatment change, n=47).
Results After 3 months, oxidized lipids were significantly decreased only in the TM group. Although the homeostasis assessment model of insulin resistance (HOMA-R) tended to be improved and serum concentrations of HDL-cholesterol and HMW adiponectin tended to be increased only in the TM group, these alterations were too small to be significant by unpaired t-test. Interestingly, in subgroup analysis, the alterations of HOMA-R, serum concentrations of oxidized lipids, and HMW adiponectin were more apparent in obese TM group subjects and the changes reached statistical significance.
Conclusion Switching from candesartan to telmisartan in obese subjects increases serum adiponectin and improves both insulin resistance and oxidative stress, while these effects were not statistically apparent in the total patient population. These results support the idea that telmisartan exerts its PPARγ enhancing activity clinically in obese type 2 diabetic patients.