Introduction: Type 2 diabetes mellitus (T2DM) and thyroid disorders are common endocrine conditions with a bidirectional relationship affecting glucose and lipid metabolism. Adiposity, particularly fat mass index (FMI), may influence thyroid function. but its association with thyroid dysfunction and glycemic control remains unclear, especially in Malaysia. This study aimed to determine the prevalence of thyroid dysfunction in T2DM and its association with glycemic control and FMI at Universiti Teknologi MARA (UiTM). Methodology: A cross-sectional study was conducted among patients with T2DM attending the Endocrine Clinic, UiTM, from December 2025 to March 2026. A total of 91 participants aged 18–70 years were recruited using convenience sampling. Demographic, clinical, anthropometric, and laboratory data were collected. Thyroid dysfunction was defined as thyroid-stimulating hormone (TSH) <0.38 or >5.33 mIU/L. Body composition was assessed using the InBody 380 to determine FMI. Data were analyzed using SPSS version 30 with descriptive statistics and Pearson correlation. Results: The prevalence of thyroid dysfunction among patients with T2DM was 7.7% (7/91), predominantly with low TSH levels. Mean hemoglobin A1c (HbA1c) in the overall study population was 7.59 ± 1.49%, and mean TSH was 1.42 ± 0.95 mIU/L, within the euthyroid range. Mean FMI was 11.95 ± 5.23 kg/m², exceeding normal ranges for both men (3–6 kg/m²) and women (5–9 kg/m²). FMI showed a positive correlation with TSH level (r = 0.379, p <0.001), indicating that higher adiposity was associated with higher TSH levels despite remaining within the euthyroid range. Pearson correlation showed a weak, non-significant negative correlation between HbA1c and TSH (r = −0.127, p = 0.229). Conclusion The prevalence of thyroid dysfunction among patients with T2DM in our cohort was relatively low at 7.7%. However, the significant correlation between FMI and TSH level, even within the euthyroid range, suggests that adiposity may exert a clinically relevant influence on thyroid function.
Diabetes Mellitus, Type 2 ; Prevalence ; Thyroid Gland ; Adipose Tissue