Objective To analyze the relationship between C-peptide and metabolic syndrome (MS) in premenopausal and postmenopausal women with type 2 diabetes mellitus (T2DM). Methods A total of 64 premenopausal and postmenopausal T2DM patients in our hospital from March 2019 to March 2021 were included in the experimental group, and 64 healthy women in the same period were selected as the control subjects. Fasting C-peptide, postprandial 2h C-peptide and blood glucose, serum inflammatory factors, blood lipid and blood pressure were detected and compared between the two groups. The incidence of MS was compared between the two groups. The relationship among fasting C-peptide, postprandial 2h C-peptide and blood glucose, serum inflammation, blood lipid and blood pressure were analyzed by Pearson correlation. Results Fasting C-peptide,postprandial 2h C-peptide, 2hPG, FPG, WBC, TNF-a, IL-6, LDL-C, TG, TC, SBP, DBP of the experimental group were higher than those of the control group. HDL-C of the experimental group was lower than that of the control group, P<0.05. The incidence of MS in the experimental group (12.50%) was higher than that in the control group (1.56%), P< 0.05. Fasting C-peptide and postprandial 2h C-peptide were positively correlated with 2hPG, FPG, WBC, TNF-a, IL-6, LDL-C, TG, TC, SBP and DBP, and negatively correlated with HDL-C (P<0.05). Conclusion The metabolic disorder of blood lipid, blood pressure, blood glucose and inflammatory reaction were common in T2DM patients before and after menopause. The increase of C-peptide level would increase the incidence of MS, which should be paid attention in clinic practice.