Anemia is inversely associated with serum C-peptide concentrations in individuals with type 2 diabetes

The purpose of the study was to test the hypothesis that anemia is related with serum C-peptide concentrations in individuals with type 2 diabetes mellitus (DM). This cross-sectional study was carried out in 1300 individuals with type 2 DM. We measured fasting C-peptide, 2-hour postprandial C-peptide, and postprandial C-peptide minus fasting C-peptide (ΔC-peptide) concentrations. Anemia was defined as hemoglobin (Hb) concentrations <130 g/L in men and <120 g/L in women. Anemia was graded into 2 groups: grade I anemia of Hb concentrations ≥110 g/L and grade II anemia of Hb concentrations <110 g/L. Fasting C-peptide, postprandial C-peptide, and ΔC-peptide concentrations were lower in individuals with anemia. According to the grade of anemia, the average C-peptide concentrations differed significantly after adjusting for other covariates. In the multivariable model, the statistically significant relation between anemia and serum C-peptide concentrations remained after adjusting for confounders, including age, gender, family history of diabetes, body mass index, duration of diabetes, glycated Hb, free fatty acids, hypertension, and hyperlipidemia (fasting C-peptide concentration: β = –0.057, P = .032; postprandial C-peptide concentration: β = –0.098, P < .001; ΔC-peptide concentration: β = –0.095, P < .001). Anemia was inversely associated with serum C-peptide concentrations in individuals with type 2 DM.