Association of serum fibroblast growth factor 21 with diabetic complications and insulin dose in patients with type 1 diabetes mellitus

Introduction Fibroblast growth factor (FGF) 21 is an important regulator of glycemic control, but the association between circulating FGF21 and diabetic complications is poorly understood. Moreover, basal FGF21 secretion, especially in response to insulin dose, in patients with type 1 diabetes mellitus (T1DM), has not been well examined. Therefore, this study aimed to determine the association of circulating FGF21 levels with diabetic complications and insulin dosage in middle-aged and elderly patients with T1DM. Materials and methods A total of 127 middle-aged and elderly patients with T1DM, including 68 patients with diabetic complications, and 106 non-diabetic individuals were analyzed in this cross-sectional study. Information on demographic characteristics and T1DM was extracted from their electronic medical records. Serum FGF21 levels were determined using ELISA. Results Serum FGF21 levels were significantly lower in T1DM patients (75.2 [37.4-135.1] pg/mL) than in non-diabetic participants (151.6 [92.0-224.6] pg/mL; P < 0.001). No diabetic complications were associated with serum FGF21 concentrations. Both basal and bolus insulin doses were significantly and positively correlated with serum FGF21 levels (P < 0.05). Stepwise multiple regression analysis showed that FGF21 level was associated with age and body mass index (P < 0.05), while the basal insulin dose was an independent positive predictor of serum FGF21 levels (beta = 0.197, P = 0.032). Conclusions Circulating FGF21 levels are reduced in patients with T1DM; however, they are not associ- ated with diabetic complications. In addition, aging, obesity, and insulin dosage are positive determinants of circulating FGF21.