Serum transforming growth factor-beta 1 levels in normoalbuminuric and normotensive patients with type 2 diabetes. Effect of metformin and rosiglitazone.

OBJECTIVE

a)To determine serum Transforming Growth Factor-beta 1 (TGF-beta 1) levels in patients with type 2 diabetes who do not have diabetes related complications and in healthy controls, b) to evaluate the effects of metformin and rosiglitazone on TGF-beta 1 levels.

DESIGN

In the washout period, 61 patients with Fasting Plasma Glucose levels (FPG) higher than 140 mg/dl, Postprandial Glucose (PPG) levels higher than 180 mg/dl and A1c levels exceeding 6.5% were treated with glimperide. After 4 weeks, 39 of these patients were randomised to receive either metformin or rosiglitazone for 12 weeks. Thirty healthy controls were also studied.

RESULTS

There were no significant differences with regard to age, gender, body weight and BMI between patients and healthy controls. Type 2 diabetics had higher waist circumference, FPG, total cholesterol, LDL-cholesterol and triglyceride levels. Baseline TGF-beta 1 levels in diabetics were higher than in controls (29.84+/-7.04 ng/ml vs 11.37+/-4.06 ng/ml, p<0.001). Metformin or rosiglitazone did not significantly modify the TGF-beta 1 levels. In a multiple regression analysis FPG was the only variable that was significantly associated with plasma TGF-beta 1 levels.

CONCLUSION

The elevated levels of TGF-beta 1 in subjects with type 2 diabetes possibly indicate a tendency for renal and endothelial damage in such patients. The association of TGF-beta 1 with FPG possibly links poor diabetic control to vascular damage, leading to diabetic complications. Lack of changes in the levels of TGF-beta 1 after therapy may reflect inadequate therapy duration.