Since the thyroid gland plays a central role in the regulation of metabolism, abnormal thyroid function can have a major impact on the control of diabetes. In addition, untreated thyroid disorder can increase the risk of certain diabetic complications and can aggravate many diabetes symptoms. Luckily, abnormal thyroid function can easily be diagnosed by simple blood tests, and effective treatment is available. For all of these reasons, periodic screening for thyroid disorder should be considered in all people with diabetes.