ABSTRACT Objectives Type 2 diabetes mellitus (T2DM) and its microvascular complications are characterized by chronic inflammation. The Controlling Nutritional Status (CONUT) score is a tool used to assess nutritional status and is often associated indirectly with inflammatory processes. We aimed to compare the CONUT scores of T2DM patients with those of healthy volunteers and to compare T2DM patients with and without microvascular complications. Methods Patients diagnosed with T2DM and healthy volunteers (as controls) were included in the study. The CONUT score is calculated using the following formula: serum albumin score + total cholesterol score + total lymphocyte count score. CONUT scores of T2DM patients and healthy controls, as well as those of diabetics with and without microvascular complications, were compared. Results The CONUT scores of the T2DM and control groups were (1 [0–7]) and (0 [0–2]), respectively (p < 0.001). The sensitivity and specificity of the CONUT score (<1.5 threshold) in detecting T2DM were 43% and 90%, respectively (AUC: 0.67, p < 0.001, 95% CI: 0.64–0.71). Moreover, the CONUT score was an independent risk factor for T2DM (OR: 0.34, p < 0.001, 95% CI: 0.22–0.52). The CONUT score of T2DM patients with microvascular complications (2 [0–7]) was significantly higher than that of T2DM patients without microvascular complications (0 [0–4]) and control subjects (0 [0–2]) (p < 0.001). A CONUT score higher than 1.5 had 83% sensitivity and 92% specificity in detecting T2DM with microvascular complications (AUC: 0.91, p < 0.001, 95% CI: 0.89–0.93). Conclusion The CONUT score could be useful in detecting diabetic microvascular complications in clinical practice, as it is an inexpensive and easy-to-assess marker.