Elevated levels of fasting serum GIP may be protective factors for diabetic retinopathy in type 2 diabetes mellitus.

Objective: Glucose-dependent insulinotropic polypeptide (GIP) is an incretin hormone which has been ascribed a positive role in cardiovascular function. However, little is known about the association between GIP and microvascular complications including retina and kidney. In the present study, we conducted a cross-sectional study to investigate the relationship between fasting serum GIP and microvascular complications in type 2 diabetes mellitus (T2DM). Methods: A cross-sectional study was performed in 295 T2DM patients in our endocrine ward in order to investigate the relationship between fasting serum GIP and microvascular complications. Results: Among the 295 T2DM patients, the levels of median fasting serum GIP of all were 431.36pg/ml, interquartile range of which were 333.26~531.96pg/ml and the prevalence of diabetic retinopathy (DR) and diabetic nephropathy (DN) were 37.63% and 38.64% respectively. Our study observed that the prevalence of DR was significantly higher in low-levels GIP group compared with those in high-levels GIP group (p=0.007) (46.26% versus 31.08%) and the levels of fasting serum GIP were also higher in T2DM patients without DR than those with DR (p=0.019) (440.99pg/ml versus 405.90pg/ml). Spearman's correlation and multiple stepwise regression analysis showed that prevalence of DR was independently and negatively correlated with fasting serum GIP in T2DM (r=−0.134, p=0.021) (DR,β= −0.279; 95% CI, −0.512~−0.047, p = 0.019). However, there were no differences in fasting serum GIP between non-proliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR) (p=0.951). Similarly, we did not find any association between fasting serum GIP and prevalence of DN by using various statistical analyses. Conclusions: Prevalence of DR was independently and negatively correlated with fasting serum GIP in T2DM, indicating that elevated levels of fasting serum GIP may act as protective factors for DR. [ABSTRACT FROM AUTHOR]