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

AbstractObjectives 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: HypothyroidismHOMA-IRinsulin resistanceMETS-IRthyroid-stimulating hormone Transparency Declaration of fundingNo funding source was received for this study.Declaration of financial/other relationshipsThe authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.Author contributionsThe author was involved in the conception, design, analysis, and interpretation of the data; the drafting of the manuscript and revising it critically for intellectual content; and the final approval of the version to be published. The authors agree to be accountable for all aspects of this work.AcknowledgementsNo assistance in the preparation of this article was declared.Data availability statementThe study data were then stored. The data supporting the findings of this study are available from the author [STK] upon reasonable request.Ethics statementThe study was conducted in accordance with ethical principles and the Declaration of Helsinki. Informed consent was obtained from all participants. The study protocol was approved by the Local Ethics Committee (Gaziosmanpaşa Training and Research Hospital, Date: 01.03.2023, Number: 24),