Hypothyroidism refers to hypothyroidism, which does not usually induce a rise in blood glucose, but may instead cause a fall in blood glucose. Thyroid hormone is the main glucose-raising hormone, and the constancy of blood glucose in the body mainly depends on the balance between glucose-raising hormone and glucose-lowering hormone. The main glucose-raising hormones include thyroid hormone, epinephrine, norepinephrine, growth hormone and glucagon, while the only hormone that lowers blood glucose is insulin. When a patient suffers from hypothyroidism, the synthesis and secretion of thyroid hormones are reduced, which can lead to a decrease of glucagon in the body, so it usually does not cause blood glucose to rise, but easily causes blood glucose to fall below normal level. The above is the general situation, but it does not exclude that some patients experience special circumstances. In the process of treatment, thyroid hormone levels need to be reviewed in a timely manner. If thyroid function is not checked in a timely manner during the treatment of hypothyroidism, or if too much levothyroid hormone is used, it may easily cause pharmacological hyperthyroidism, which may induce secondary diabetes. Thyroid hormones are glucagon hormones, and too much glucagon hormone will counteract insulin, thus leading to secondary hyperglycemia in patients. In hypothyroid patients with secondary hyperglycemia, the symptoms of hyperglycemia can be relieved by gradually reducing the amount of levothyroid hormone so that the thyroid hormone level returns to the normal range. The regulation of blood glucose is closely related to the amount of food eaten and whether insulin secretion is normal or not, but has little effect on thyroid hormone. Therefore, hypothyroid patients usually do not have elevated blood glucose. If hypothyroid patients have elevated blood glucose at the same time, it is necessary to check whether the patient has abnormal glucose metabolism or combined with diabetes.