Insulin resistance in non-diabetic hypothyroid patients: a critical examination of METS-IR as a diagnostic marker

Abstract

Objectives Insulin resistance (IR) is a significant metabolic disturbance that plays a pivotal role in various health conditions, including hypothyroidism. Homeostatic Model Assessment For Insulin Resistance (HOMA-IR) is widely used for assessing IR. However, alternative indices, such as the Metabolic Score for Insulin Resistance (METS-IR), have been developed for diverse applications. This study aimed to meticulously investigate IR in patients with hypothyroidism and to compare the effectiveness of METS-IR with HOMA-IR. To enrich our analyses, additional metrics, including the Triglyceride Glucose (TyG) Index, the Triglyceride to High-Density Lipoprotein Cholesterol Ratio (TG/HDL-C), and the Quantitative Insulin Sensitivity Check Index (QUICKI) have been incorporated. Methods This cross-sectional study included 260 non-diabetic adults, 130 with hypothyroidism (case group), and 130 healthy volunteers (control group). Parameters, including Thyroid-Stimulating Hormone (TSH), free thyroxine (T4), fasting blood glucose, HbA1c, insulin levels, and lipid profiles, were measured. IR indices were calculated. Results The groups were matched for age and gender (p = .143; p = .099). The case group demonstrated a notably elevated mean METS-IR of 195.58, in contrast to the control group’s mean METS-IR of 131.10 (p = .044). The mean HOMA-IR was significantly higher in the case group than in the control group, with average of 2.00 and 1.81, respectively (p = .027). METS-IR was positively correlated with TyG (r = 0.505, p = .001) and TG/HDL-C (r = 0.844, p = .001). Meanwhile, the relationships between METS-IR, HOMA-IR, and QUICKI were significant at r = 0.194 (p = .027) and r = .210 (p = .016), respectively. METS-IR was significantly higher in patients with overt hypothyroidism (p = .016). Conclusion This study emphasizes the efficacy of METS-IR as a diagnostic tool for IR in patients with hypothyroidism, establishing it as a proficient alternative to HOMA-IR. These findings were substantiated by the correlations observed with the TyG, TG/HDL-C, and QUICKI measurements. Variations in METS-IR between individuals with subclinical and overt hypothyroidism accentuate its effectiveness in identifying metabolic abnormalities in hypothyroid conditions.