Objective To observe the effect of urinary albumin on skeletal muscle mass in middle-aged and elderly male patients with newly diagnosed type 2 diabetes mellitus (T2DM). Methods A total of 96 middle-aged and elderly male patients (≥45 years old) with newly diagnosed T2DM for less than 1 year in our hospital from March 2019 to August 2020 were enrolled in this study. According to the presence or absence of albuminuria, they were divided into non-albuminuria group (n=50) and albuminuria group (n=46). Their fasting blood glucose (FBG), total cholesterol (TC), triglyceride (TG), serum creatinine (SCr), limb muscle mass, and limb appendicular skeletal muscle mass index (ASMI) and other clinical indicators were measured. SPSS statistics 19.0 was used to perform the statistical analysis. Multiple linear regression was used to analyze the independent correlation between urinary albumin and ASMI. Results Fasting insulin (FINS), homeostatic model assessment of insulin resistance (HOMA-IR), low-density lipoprotein cholesterol (LDL-C), uric acid (UA), SCr, and urinary albumin creatinine ratio (UACR) were significantly higher (t=2.762-13.343, all P<0.05), but limb muscle mass, ASMI and glomerular filtration (GFR) were obviously lower (t=5.539-6.953, all P<0.05) in the albuminuria group than the non-albuminuria group. UACR was positively correlated with HOMA-IR, UA and SCr (r=0.223-0.426, all P<0.05), and negatively with limb muscle mass, ASMI and GFR (r=-0.287--0.490, all P<0.05). Multiple linear regression analysis showed that UACR was an independent influencing factor of ASMI (β=0.389, P=0.014). Conclusion UACR is negatively correlated with ASMI in middle-aged and elderly male patients with T2DM. Urinary albumin is an independent factor for ASMI in those with newly diagnosed T2DM.