Hyperthyroidism and diabetes mellitus are both endocrine metabolic diseases, and both can show symptoms of wasting, overeating and weakness. The differentiation between hyperthyroidism and diabetes is mainly based on the following points: 1. age and gender of onset, hyperthyroidism occurs more often in young and strong women, while diabetes has no age or gender difference. 2. clinical symptoms, hyperthyroidism mainly manifests itself as hypermetabolic syndrome such as fear of heat, excessive sweating, emaciation, increased frequency of stools, agitation, protrusion of eyes, and goiter. Diabetes mellitus is mainly characterized by “3 more and 1 less” symptoms, i.e. polyphagia, polyuria, polyhydramnios, lethargy, etc. It can be accompanied by blurred vision and numbness of both lower limbs, or no symptoms at all. 3. Laboratory tests: Diabetic patients mainly show elevated fasting and postprandial glucose and glycated hemoglobin. In contrast, hyperthyroidism is mainly characterized by abnormal thyroid function, mainly elevated T3 and T4 and reduced TSH.