Non-alcoholic Fatty Liver Disease in Patients With Type 2 Diabetes Mellitus: A Cross-Sectional Study Assessing Metabolic Indices and Microvascular Complications

Background and objectives Liver fibrosis is a key stage in chronic liver disease progression, marked by excessive extracellular matrix (ECM) deposition that disrupts liver architecture. Non-alcoholic fatty liver disease (NAFLD), a hepatic manifestation of metabolic syndrome, is a growing global health concern. This is especially true for individuals with type 2 diabetes mellitus (T2DM). Chronic hyperglycemia in T2DM may accelerate hepatic fibrogenesis. This happens through oxidative stress, inflammation, and impaired lipid metabolism. We aimed to determine the prevalence of NAFLD, hypertension, and microvascular complications among individuals with T2DM. We assessed their clinical parameters, such as glycemic, lipid, renal, and hepatic values. We also computed and compared the following metabolic indices among patients with and without NAFLD: NAFLD fibrosis score (NFS), fibrosis-4 (FIB4) index, fatty liver index (FLI), and metabolic score for insulin resistance (METS-IR). We further assessed correlations among various clinical parameters and metabolic indices. In addition, we calculated sensitivity, specificity, diagnostic accuracy, and the area under the curve (AUC) for these metabolic indices through a receiver operating characteristic (ROC) curve. Methods This cross-sectional study took place at Kalinga Institute of Medical Sciences (KIMS), Bhubaneswar, India, from March 2023 to February 2025. We reviewed adult diabetic patients of both sexes attending our medicine and endocrinology outpatient departments (OPDs) during the study period. We assessed patients referred for ultrasonography to rule out NAFLD. We evaluated clinical parameters and metabolic indices in patients with and without NAFLD. Associations were measured with Spearman’s correlation. We calculated the sensitivity, specificity, AUC, and diagnostic accuracy for these indices. R software (version 4.5.3; R Foundation for Statistical Computing, Vienna, Austria) was used for data analysis. Results Among 401 patients with diabetes (median age 68.0 years), 166 (41.4%) were male. NAFLD was present in 115 (28.7%), and hypertension in 183 (45.6%). Neuropathy, nephropathy, and retinopathy affected 147 (36.7%), 142 (35.4%), and 102 (25.4%) of patients, respectively; these rates were higher in those with NAFLD. Patients with NAFLD had higher median glycated hemoglobin (9.11% vs. 8.61%, p < 0.001), METS-IR (48.22 vs. 47.21, p = 0.024), FLI (66.20 vs. 54.55, p < 0.001), FIB4 (1.02 vs. 0.85, p = 0.010), and NFS (1.39 vs. 1.06, p = 0.002) compared to those without NAFLD. Strong positive correlations were observed between FLI and METS-IR (r = 0.88) and NFS and FIB4 (r = 0.87). FLI and METS-IR showed higher specificity (0.8252 and 0.7630) and accuracy (0.7481 and 0.6434), while FIB4 and NFS had moderate sensitivity and diagnostic accuracy. All indices had similar AUC values (range: 0.5723-0.6222). Conclusion The study found that chronic hyperglycemia is closely associated with increased liver fibrosis, as reflected in higher metabolic index values among patients with NAFLD. Metabolic indices such as FLI, METS-IR, FIB4, and NFS showed moderate utility as non-invasive markers for glycemic control and fibrosis risk. Incorporating fibrosis assessment into routine diabetes management could enable earlier detection and intervention. The findings underscore the importance of further longitudinal studies to clarify whether improved glycemic control can reverse liver fibrosis.