[Serum level of retinol-binding protein 4 in obese patients with insulin resistance and in patients with type 2 diabetes treated with metformin].

OBJECTIVE

Is there a difference between the retinol-binding protein 4 (RBP4) levels in obese patients with insulin resistance (IR) without diabetes, in obese patients with type 2 diabetes mellitus (DM2T) treated with metformin and in nonobese healthy individuals?

METHOD

28 obese individuals with insulin resistance, 11 type 2 diabetes patients treated with metformin and 17 control individuals were examined for serum level of retinol-binding protein 4 using the RIA method. The results were compared within the groups and RBP4 was correlated with insulin in the IR group and the control group.

OUTCOME

The highest and the lowest RBP4 levels (561.6 +/- 209 ng/ml) were recorded, respectively, for obese individuals with IR (IR HOMA 3.9) and for obese type 2 diabetics treated with metformin (391.1 +/- 133,5 ng/ml) (P < 0.01). The RBP4 level of the control group was significantly lower as compared with the obese individuals with IR (452.8 +/- 104.6 ng/ml) (P < 0.05), but insignificantly higher as compared with the obese individuals with DM2T treated with metformin (391,1 +/- 133.5 ng/ml). RBP4 in the monitored group correlated with insulin r = 0.46 (p < 0.03).

CONCLUSION

The increase in RBP4 in obese individuals by GLUT4 regulation in adipocytes contributes to the development and aggravation of systemic IR. Through its effect on RBP4 expression in adipocytes, metformin may improve total insulin sensitivity in obese individuals including those with MS and delay the onset of manifest DM. RBP4 could by used as a marker of deteriorating glucose tolerance in obese individuals.