Diabetes mellitus and thyroid disorders are both common endocrine diseases. In recent years, with the improvement of people’s living standard and the change of diet structure, the incidence of both diseases has increased significantly. Today, the incidence of thyroid gland in Chinese people is increasing, with about 50% to 80% of women and 40% to 60% of men over 60 years old having thyroid nodules. According to the epidemiological survey of thyroid diseases in China, the prevalence of hypothyroidism in Chinese people has reached 6.5%, and the prevalence of hyperthyroidism is also as high as 3.7%. More seriously, thyroid cancer has become a common head and neck malignant tumor, accounting for about 35% of all head and neck malignant tumors. In our daily outpatient work, we often encounter patients with diabetes who also have thyroid disease. Many patients ask: “What is the relationship between thyroid disease and diabetes? Why do I have both diseases at the same time? If I have diabetes and hyperthyroidism, will I continue to lose weight? How do I treat it? What should I pay attention to in my life ……” Diabetics are prone to thyroid disease Thyroid disease is not a complication of diabetes, but thyroid disease, especially hyperthyroidism or hypothyroidism, occurs more often in diabetics. As early as 1867, Dumonptllier, a foreign scholar, first reported a case of hyperthyroidism combined with hypoglycemic tolerance, and since then many scholars have conducted statistical analyses of large groups of diabetic populations. Some experts found that 3.2% of the 1882 diabetic patients had hyperthyroidism. Other scholars found that 4.0% of 255 diabetic patients suffered from hypothyroidism …… From the above information, we can see that the incidence of diabetes combined with hyperthyroidism and hypothyroidism is much higher than that of non-diabetic people. It can be said that they are a pair of difficult brothers and sisters, they appear at the same time in the same patient, and affect each other to aggravate the disease and make our treatment more difficult. At present, the exact etiology and pathogenesis of diabetes mellitus combined with thyroid disease are still unclear. Most scholars believe that the two diseases have a common genetic and immunological basis. For example, the incidence of diabetes in close relatives of hyperthyroid patients is 33%-36%; there is a clear family history of both hyperthyroidism and diabetes; it has been reported that antithyroid antibodies can be detected in the serum of people with type 1 diabetes, and 47 of 117 type 1 diabetic patients with positive antithyroid microsomal antibodies were diagnosed with thyroid disease. A possible reason why thyroid disease occurs more frequently in diabetic patients is that they are all autoimmune abnormality-associated diseases. Diagnostic considerations When diabetes mellitus is combined with hyperthyroidism, the clinical manifestations of both can be atypical, showing only wasting, overeating and excessive sweating; if the diabetic patient has good glycemic control and the hyperthyroid patient has normal hyperthyroid function after treatment and does not gain weight, attention should be paid to the relevant tests. 1, diabetes and hyperthyroidism have a lot of similar clinical symptoms in the early stage, especially in elderly people with atypical symptoms of hyperthyroidism, often easy to miss the diagnosis. Therefore, diabetic patients with poorly controlled blood sugar for a long time, especially the elderly, should think about the possibility of both diseases existing at the same time. Low serum total triiodothyronine (T3) may occur in poorly controlled diabetes. Therefore, those with mildly elevated serum T3 should be reviewed with attention and the diagnosis of hyperthyroidism should not be easily abandoned. 2. Patients with hyperthyroidism can develop disorders of glucose metabolism, and such changes will return to normal after the hyperthyroidism is controlled. However, long-term abnormal glucose metabolism in hyperthyroidism may lead to further failure of pancreatic islet B-cell function and develop into diabetes. Therefore, if a hyperthyroid patient has elevated blood glucose and abnormal glucose tolerance, and if his blood glucose does not decrease after the symptoms of hyperthyroidism are controlled, he should be diagnosed as having hyperthyroidism combined with diabetes mellitus. 3, diabetes combined with hypothyroidism is often easy to miss the diagnosis, probably because the onset of hypothyroidism is often insidious, and early symptoms are generally not taken seriously by patients and doctors. If a diabetic patient has weight gain with symptoms such as chills and edema, T3, serum total tetraiodothyronine (T4) and thyroid stimulating hormone (TSH) should be measured promptly to make early diagnosis of mild and subclinical hypothyroidism. Considerations for treatment Hyperthyroidism can make the clinical manifestations of diabetes more prominent in some people who do not have diabetic symptoms, and can also worsen diabetic symptoms. Poorly controlled diabetes mellitus may trigger a thyroid crisis. Therefore, it is necessary to treat both diseases simultaneously. The treatment of diabetes should be chosen at your discretion. Because of the hyper-metabolism and high consumption when combined with hyperthyroidism, diabetic diet treatment should be relaxed appropriately and adjusted accordingly when the hyperthyroidism is controlled. In some patients, after the symptoms of hyperthyroidism are controlled, oral hypoglycemic drugs and insulin should be reduced or discontinued appropriately. When the two diseases coexist, the course of hyperthyroidism medication should be extended to reduce the recurrence rate of hyperthyroidism. When combined with hypothyroidism, treatment with thyroxine tablets can cause worsening of diabetic symptoms and difficulty in controlling blood sugar. Therefore, the treatment of hypothyroidism should increase the dose of glucose-lowering drugs or even need to switch to insulin therapy. In conclusion, we should pay attention to the co-existence of diabetes and thyroid disease in one body, recognize and diagnose them early, pay attention to the special features of their treatment, and cultivate a good lifestyle to reduce the occurrence of diabetes or/and thyroid disease, so that we can’t let the difficult brothers and sisters to be together!