Elevated thyroid-stimulating hormone correlates with insulin resistance and β-cell dysfunction in type 2 diabetes...

To investigate the correlation between thyroid-stimulating hormone (TSH) levels and insulin function indices, including the homeostatic model assessment of insulin resistance (HOMA-IR) and β-cell function (HOMA-ISLET), in patients with type 2 diabetes mellitus (T2DM) complicated by subclinical hypothyroidism (SCH), and to evaluate their diagnostic value for identifying elevated TSH states.

A total of 384 T2DM patients treated between April 2022 and November 2024 were retrospectively analyzed. Among them, 184 patients with SCH comprised the combined group, and 200 patients with T2DM alone comprised the diabetes group. Demographic data, fasting plasma glucose (FPG), fasting insulin (FINS), and TSH were collected to calculate HOMA-IR and HOMA-ISLET. Inter-group comparisons, correlation analyses, and receiver operating characteristic (ROC) curve analyses were performed.

Compared to the diabetes group, the combined group showed significantly higher TSH, HOMA-IR, and HOMA-ISLET (all P < 0.001). TSH correlated positively with HOMA-IR and negatively with HOMA-ISLET (combined group: r = 0.587 and -0.464; diabetes group: r = 0.334 and -0.545; all P < 0.001). ROC analysis demonstrated favorable diagnostic performance for HOMA-IR (AUC = 0.720 for SCH; 0.892 for elevated TSH) and HOMA-ISLET (AUC = 0.711 for SCH; 0.878 for elevated TSH). HOMA-IR showed stronger discriminative ability than HOMA-ISLET in distinguishing diabetes-only from high TSH states (AUC = 0.928 vs. 0.709).

Elevated TSH levels are closely associated with increased insulin resistance and impaired β-cell function in T2DM. Both HOMA-IR and HOMA-ISLET are valuable diagnostic tools, with HOMA-IR demonstrating superior clinical applicability for detecting T2DM with SCH and elevated TSH states.