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.

Keywords: HOMA-IR; Hypothyroidism; METS-IR; insulin resistance; thyroid-stimulating hormone.