Background: The thyroid gland is classified as one of the important endocrine glands in the human body, as it is regulated by a hormone known as thyroid stimulating hormone (TSH) secreted by the anterior lobe of the pituitary gland. The thyroid gland acts to secrete the hormone thyroxine (T4). Then it converts to triiodothyronine (T3) which is responsible for many functions in the body, but the most important of these functions is regulating metabolism in the body. Materials and Methods: This study collected samples from healthy people (the first group) and people with T1D (the second group). Blood samples were taken from both groups after their members agreed to join the study, and biochemical markers were measured for all members of both groups in the serum samples, including random blood sugar (RBS), Insulin hormone (Ins. H.), C-peptide, TSH, T4, and T3. Results: After doing statistical analysis, the current study showed that there are clinically significant differences between the two groups, which are as follows: *An increase in the level of RBS and TSH in the second group compared to the first group and *A decrease in the level of Ins.H., C-peptide, T4 and T3 in the second group compared to the first group.
Conclusion: The study concluded that there is an association between the absence of insulin in patients with T1D and hypothyroidism. This study showed that insulin has an important role in the process of regulating the production of thyroid hormones.