Objective To explore the relationship between the first-phase insulin secretion and diabetic microvascular complications in patients with type 2 diabetes mellitus (T2DM) using arginine stimulating test. Methods Sixty-seven patients with T2DM, aged (56.4±14.2) years, were enrolled from the Affiliated Hospital of Nantong University, and they included 42 males and 25 females. The patients with microvascular complications were assigned to case group (n=23), and the patients without microvascular complications were assigned to control group (n=44). The parameters, including height, body mass, duration of diabetes, renal function, plasma lipids, urinary microalbumin, and urine creatinine, were collected. Body mass index (BMI), urinary microalbumin/creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR) were calculated. The arginine stimulating test was performed in the fasting state. The levels of plasma glucose, and serum insulin and C-peptide were tested in the fasting state, and at 2, 4 and 6 min after injecting arginine. The acute insulin response (AIR) index, acute C-peptide response (ACR) index, area under curve of insulin (INS_AUC) and homeostasis model assessment of insulin resistance (HOMA-IR) index were calculated, and their correlations with diabetic microvascular complications were analyzed. Results The duration of diabetes of the T2DM patients in the case group was significantly longer than that in the control group (P=0.030). Compared with the control group, the serum creatinine level, UACR, serum insulin and C-peptide levels (in the fasting state and at 2, 4, 6 min after injecting arginine), AIR index, INS_AUC, and HOMA-IR index were higher, and the eGFR was lower in the case group, and the differences were significant (all P<0.05). The logistic regression analysis after adjusting for age and BMI showed that the duration of diabetes and AIR index were significantly correlated with the diabetic microvascular complications (odds ratio[OR]=1.099, 95% confidence interval[CI] 1.011-1.194, P=0.026; OR=1.049, 95% CI 1.007-1.092, P=0.021). Conclusion The diabetic microvascular complications are associated with the long duration of diabetes and high AIR index in the patients with T2DM.