Thyroid Dysfunction, Remodeling, and Trends in Dysfunctional Thyroid Between People with Diabetes Mellitus Type 1 And Type 2

Background: Diabetes mellitus and thyroid dysfunction are two of the most prevalent endocrine disorders across globe, and concurrence of them may cause worsening metabolic control and increased morbidity. Thyroid hormone changes differ among types of diabetes, gender, and related biochemical derangements.Objective: Aim This study was to assess the thyroid function and frequency of thyroid dysfunction in type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) patients compare to non-diabetic clinic controls.Methods: It is a case-control study carried on two hundred participants, from them one hundred controls and one hundred patient in the Diabetes Center in Al-Sadr General Hospital in Najaf Al-Ashraf in the period from May 2025 to August 2025. This study consisted of 50 patients of type 1 diabetes mellitus, 50 patients of type 2 diabetes mellitus and 100 non- diabetic controls. Thyroid function was determined by serum levels of thyroid-stimulating hormone, free triiodothyronine and free thyroxine. Furthermore, laboratory investigations such as fasting blood glucose, postprandial blood glucose, glycated hemoglobin, lipid Profile, serum urea, creatinine and urinary microalbumin were studied by standard laboratory techniques.Results: Of the groups studied, thyroid hormone levels differed significantly. In patients with type 2 diabetes mellitus, thyroid-stimulating hormone was elevated and free triiodothyronine and free thyroxine levels were reduced to a greater degree in females, indicating a more hypothyroid pattern. In comparison, at the opposite end of the spectrum, type 1 diabetes mellitus patients had higher free thyroid hormone levels (specifically FT3 and FT4) and lower TSH values, suggesting the potential for hyperthyroid function to be a problem. About half of the patients with type 2 diabetes mellitus (more frequently females) had a higher prevalence of hypothyroidism, while the frequency of hyperthyroidism was greater in females with type 1 diabetes mellitus. Patients with diabetes also showed a significantly higher fasting blood glucose, postprandial blood glucose, glycated hemoglobin and lipid profile disorders compared with the controls.Conclusions: The results show that thyroid function is profoundly altered in diabetic patients, being that differences are presented regarding type 1 and type 2 diabetes. Hypothyroid changes were more often associated with type 2 diabetes mellitus, especially in females, whereas type 1 diabetes mellitus was associated with a trend towards hyperthyroid changes. In conclusion, routine thyroid function screening is clinically useful to facilitate case finding for early diagnosis and better disease management in diabetic patients.