Abstract:Objective To investigate the correlation between skeletal muscle mass and islet function, skeletal muscle mass and insulin resistance in patients with type 2 diabetes mellitus (T2DM), and to elaborate on the clinical significance of skeletal muscle mass in the maintenance of blood glucose homeostasis. Methods A total of 274 adult T2DM patients hospitalized in the Department of Endocrinology, the First Affiliated Hospital with Nanjing Medical University from August 2023 to February 2024 were retrospectively analyzed. The basic information of patients was collected, the grip strength of patients was measured, and the blood and urine samples were taken for biochemical detection. Bioelectrical impedance analysis (BIA) was used to measure the skeletal muscle content of the upper and lower limbs, visceral fat area (VFA) and waist circumference fat weight. The skeletal muscle mass index (SMI) and appendicular skeletal muscle mass index (ASMI) were calculated, respectively. Pearson correlation method was used to analyze the correlation of grip strength, SMI and ASMI levels with blood glucose, insulin and C-peptide levels, islet β cell function indicators ［islet β cell function (HOMA-β), corrected insulin reactivity (CIR), insulinogenic index (IGI)］, and homeostasis model assessment of insulin resistance (HOMA-IR) and insulin sensitivity index(ISI). Multirariable linear regression was further used to analyze the correlation between skeletal muscle mass and islet function in T2DM patients with different VFA and BMI. Results In T2DM patients, fasting blood glucose and insulin, 120-minute postprandial blood glucose, and HOMA-IR were negatively correlated with grip strength levels (P＜0.05), while 120-minte postprandial insulin was positively correlated with grip strength levels (P＜0.05). SMI and ASMI were negatively correlated with blood glucose levels at different time points of glucose tolerance in T2DM patients (P＜0.01), and positively correlated with serum C-peptide levels, HOMA-β, CIR, and IGI, respectively (P＜0.05). The level of SMI in lower limbs was negatively correlated with blood glucose, at different time points of glucose tolerance (P＜0.01), and positively correlated with insulin, C-peptide at different time points, as well as HOMA-β, IGI and CIR in T2DM patients (P＜0.05); However, except for the negative correlation between SMI level of upper limbs and 120 min blood glucose (P=0.019), there was no correlation between SMI level and other indicators mentioned above (P ＞0.05). After adjusting for gender and age, BMI stratified analysis showed that the correlations of SMI level with HOMA-β, IGI and CIR were significant in the normal BMI subgroup (P_*<0.05), but not significant in the overweight and obese subgroups (P_*＜0.05), while the correlations of SMI level with HOMA-IR , ISI were not significant in the normal BMI subgroup (P_*>0.05), but significant in the overweight and obese subgroups (P_*>0.05). Conclusion Skeletal muscle mass is closely associated with blood glucose, islet function and insulin resistance in patients with T2DM. Increasing skeletal muscle mass of the whole body, especially that of the lower limbs and reducing the fat content accordingly play critical roles in the maintenance of glycemic homeostasis and improving islet function in patients with T2DM.