Plasma concentration of cyclic glycine proline is associated with impaired energy metabolism in a Chinese population of type 2 diabetes mellitus

Abstract

Insulin-like growth factor (IGF)-1 is an effector of cyclic glycine-proline (cGP) and regulates glucose metabolism and vascular remodeling. This study investigated the potential relationships of plasma concentrations of IGF-1, IGF binding protein-3 (IGFBP-3) and cyclic glycine-proline (cGP) to glucose intolerance and clinical vascular complications in a Chinese population of type - 2 diabetes mellitus (T2DM).

The study included the participants with T2DM only (n = 20), T2DM + hypertension (n = 20), T2DM + hypertension + diabetic peripheral neuropathy (DPN, n = 19) and 18 age-matched healthy controls. Fasting blood and spot urine samples were used for analysis.

Plasma concentration of cGP was positively associated with plasma concentrations of fasting glucose (p < 0.001), triglyceride (p < 0.001), HBAc-1 (%, p < 0.001), triglyceride/glucose index (p < 0.001), plasma concentrations of uric acid (p = 0.002), urine albumin (p = 0.008), and albumin/creatinine ratio (p = 0.019) in the T2DM only group. Plasma concentration of IGFBP-3 was positively associated with blood urea nitrogen in T2DM + hypertension group (p < 0.001) and weakly associated foot DPN scores (p = 0.052) in the T2DM + hypertension + DPN group.

Elevated plasma cGP concentration that increases the amount of bioavailable IGF-1 was an adaptive response to glucose intolerance, hyperuricemia and albuminuria. Elevated plasma IGFBP-3 concentration that reduces the amount of bioavailable IGF-1, was associated with diabetic nephropathy and peripheral neuropathy. The changes of plasma concentration of cGP and IGFBP-3 may collectively assist in the prognosis of T2DM.