Elevated levels of leptin and insulin but not of TNF alpha are associated with hypertension in type 2 diabetic males

Leptin and TNF alpha are thought to influence blood pressure. Therefore, th e aim of our study was to investigate leptin and TNF alpha levels and their association with blood pressure, sex steroids, insulin, creatinine and lip ids in type 2 diabetic patients. In 424 type 2 diabetic patients (79 hypert ensive females [+Hf], 79 normotensive females [-Hf]; 133 hypertensive males [+Hm], 133 normotensive males [-Hm]) matched for sex, age and BMI serum le ptin levels were measured by RIA and TNF alpha, insulin, estradiol, progest erone by ELISA as well as free testosterone by RIA. Leptin levels were comp arable in +Hf and -Hf(16.5 +/- 1.0 mu g/l vs 16.3 +/- 1.0 mu g/l) but highe r in +Hm as compared to -Hm (8.3 +/- 0.47 mu g/l vs 6.5 +/- 0.34 mu g/l; p < 0.05). In addition, in comparison to -Hm serum levels of insulin (190 +/- 10 pmol/l vs 161 +/- 11 pmol/l; p < 0.005) and also of creatinine (118.6 /- 3.6 mu mol/l vs 101.7 +/- 2.3; p < 0.0001) were higher in +Hm. Pearson's Correlation coefficient revealed a positive correlation between levels of leptin and diastolic brood pressure (p < 0.05) and also between leptin and insulin (p < 0.001) in males, however, only before correction for BMI. No c orrelation between leptin and creatinine was found in males and females. Le vels of TNF alpha were comparable in all subgroups. No correlation between levels of TNF alpha and serum leptin levels, blood pressure and insulin was found. In females TNF alpha was positively correlated with creatinine (p < 0.001) and in males positively with progesterone (p < 0.001). Taken togeth er, higher serum leptin levels were found in hypertensive type 2 diabetic m ales as compared to normotensives, which may be related to the BMI and high er levels of insulin. These findings are accompanied by a trend to lower le vels of free testosterone in hypertensive type 2 diabetic males. TNF alpha levels were comparable in female and male hypertensive and normotensive typ e 2 diabetic subjects.