To analyze the correlation between serum insulin-like growth factor-1 (IGF-1) levels and carotid unstable plaques in patients with type 2 diabetes mellitus (T2DM). Methods: A total of 213 T2DM patients admitted to the Department of Endocrinology at Xiaogan Central Hospital from February 2022 to February 2023 were selected. Bilateral common carotid arteries, bifurcations, and internal and external carotid arteries were examined using color Doppler ultrasound. Based on the characteristics of the ultrasound images, the subjects were divided into three groups: no plaque group (73 cases), stable plaque group (51 cases), and unstable plaque group (89 cases). Clinical data, laboratory indicators, and serum IGF-1 levels were detected and compared among the groups. Spearman correlation analysis was used to investigate the relationship between serum IGF-1 levels and various indicators in T2DM patients with carotid unstable plaques. Multivariate logistic regression analysis was used to identify the influencing factors of carotid plaque instability in T2DM patients. Results: Compared with the no plaque group, the stable plaque group had higher levels of age, systolic blood pressure, glycosylated hemoglobin (HbA1c), triglycerides (TG), and low-density lipoprotein cholesterol (LDL-C), but lower levels of IGF-1; the unstable plaque group also had higher levels of age, HbA1c, TG, and LDL-C, but lower levels of IGF-1, with statistically significant differences (P<0.05). Compared with the stable plaque group, the unstable plaque group had higher levels of HbA1c, TG, and LDL-C, but lower levels of systolic blood pressure and IGF-1, with statistically significant differences (P<0.05). Spearman correlation analysis showed that serum IGF-1 levels in T2DM patients with carotid unstable plaques were negatively correlated with age, systolic blood pressure, HbA1c, and LDL-C (P<0.05). Logistic regression analysis indicated that serum HbA1c, LDL-C, TG, and IGF-1 were influencing factors for carotid plaque instability in T2DM patients (P<0.05). Conclusion: Low levels of IGF-1 may be a contributing factor to the instability of carotid artery plaques in patients with type 2 diabetes and can aid in the assessment of plaque formation and progression.