To explore the risk factors of malnutrition in type 2 diabetes mellitus combined with pulmonary tuberculosis (PTB-T2DM) patients and further to provide a clinical research basis for the identification and prevention of malnutrition. From January 2020 to February 2022, 307 adult patients diagnosed with PTB-T2DM were enrolled in this retrospective study. According to whether malnutrition occurred after 6 months of treatment, patients were divided into malnutrition group (n = 123) and non-malnutrition group (n = 184). The nutritional status of patients was evaluated according to the Micro-Nutrition Assessment Scale (MNA). Evaluation of indicators was performed, including general information, disease characteristics of PTB-T2DM and laboratory indicators. Univariate logistic regression analysis showed that drinking, divorced, BMI <18.5kg/m2, weight <45kg, waist circumference <79cm, hip circumference <88cm, waist-to-hip ratio <69.99, calf circumference <26kg, grip strength <28kg, NRS score ≥3, Hb <106g/L, Alb <29.00g/L, PA <48.00μmol/L, GHB <3.40%, serum transferrin <1.37 mmol/L, serum potassium <3.18mmol/L, serum sodium <142.95 mmol/L, FEV1 ≥67.90% and RV <2.89% were risk factors for malnutrition in PTB-T2DM patients (all P < 0.05). The results of multivariate logistic regression analysis showed that drinking, divorced, weight <45kg, BMI <18.5kg/m2, NRS score ≥3, Hb <106g/L, Alb <29.00g/L, PA <48.00μmol/L, serum transferrin <1.37mmol/L, FEV1 ≥67.90% and RV <2.89% were independent risk factors for malnutrition in PTB-T2DM patients (all P < 0.05). Drinking, divorced, weight <45kg, BMI <18.5kg/m2, NRS score ≥3, Hb <106g/L, Alb <29.00g/L, PA <48.00μmol/L, serum transferrin <1.37mmol/L, FEV1 ≥67.90% and RV <2.89% may be independent risk factors for malnutrition in PTB-T2DM patients, and timely identification of high-risk groups could improve the prognosis of PTB-T2DM patients.