Infection is the most common complication of diabetes mellitus and is more likely to occur especially in cases of trauma, with an incidence of about 33%-90%. Among them, respiratory infections have the highest incidence, followed by urinary tract infections. Many diabetic patients are found to have diabetes because of recurrent urinary tract infections and long-lasting skin and soft tissue infections, followed by further investigations. Hyperglycemia is an important source of infection, followed by metabolic disorders, vasculopathy, neuropathy, changes in the body’s defense function and abnormalities in the activity of certain enzymes caused by diabetes mellitus. In vitro experiments have confirmed that the phagocytosis of staphylococci and Escherichia coli by leukocytes in the blood is significantly inhibited when the blood glucose exceeds two to seven times the normal value. This situation can be alleviated when poorly controlled diabetes with ketosis is controlled and corrected. Diabetic patients are prone to various infections, which in turn aggravate diabetes. The two are causal and affect each other, thus forming a vicious circle. Among the respiratory infections, pneumonia, tuberculosis, chronic bronchitis co-infection and lung abscess are the most common, followed by tuberculosis. Pneumonia can occur repeatedly due to diminished immune function. Some people have a chronic bronchitis base, which is especially common in smokers. In addition to the common pneumococci, Gram-negative bacillary infections and staphylococcal infections are also quite common, and in recent years, Klebsiella groups are also more common. The use of drugs that generally target pneumococci is often ineffective. According to statistics, the incidence of tuberculosis in diabetic patients is two to four times higher than in non-diabetic patients. Due to weakened immune function, TB in diabetic patients is prone to spread and is not easily controlled, and cavities are easily formed. In order to detect tuberculosis early, treat it early and control its development, it is advisable for diabetic patients with pulmonary symptoms to have regular chest X-ray, as well as routine blood tests and sputum culture. Diabetic patients are prone to urinary tract infections. These include urethritis, cystitis, prostatitis and pyelonephritis. Cystitis and pyelonephritis are the most common, with an incidence of about 40%. In addition to systemic immune function, as diabetes is a good medium for bacteria, which is also one of the factors that cause urinary tract infections, especially in women are more common, which is related to the wide and short urethra of women. This is related to the wide and short urethra of women. When sexual intercourse compresses the urethra, bacteria can easily enter the bladder. In addition, factors such as pregnancy and childbirth can also compress the ureter, resulting in poor urination and easy growth and reproduction of bacteria in the urine, leading to urinary tract infections. In addition to cystitis, it can also cause acute pyelonephritis. It can recur and become a refractory and complicated urinary tract infection. Women with recurrent urinary tract infections should be routinely checked for blood sugar to rule out diabetes. Diabetic women should pay special attention to perineal hygiene and urinate promptly after sex, using urine to flush out bacteria that have entered the bladder. It is important to drink more water appropriately to reduce urinary retention. After performing catheterization and gynecological examination, it is advisable to take antibacterial drugs to prevent infection. The typical symptoms of urinary tract infection are frequent and painful urination with or without fever. However, due to peripheral neuropathy caused by diabetes mellitus, many patients have no conscious symptoms. Therefore, diabetic patients, especially female patients, should go to the hospital frequently for routine urination or urine culture for timely detection and early treatment. Combined biliary tract infections are also common in diabetic patients, which are related to diabetic vegetative neuropathy leading to plant nerve dysfunction. Due to poor gallbladder contraction, delayed bile evacuation and retention, bacterial infections are very likely to develop. For the same reason, the incidence of cholelithiasis is also higher in diabetic patients, which in turn is prone to co-infection of the biliary tract. Soft tissue skin infections, such as folliculitis and carbuncles, often occur in diabetes mellitus and are recurrent and persistent. Attention should be paid to keeping the skin clean, bathing frequently, and changing underwear. If fungal infections, such as mycosis fungoides, occur in diabetic patients, they can often cause itching of the perineal skin due to the stimulation of urine sugar and leucorrhoea. In addition, diabetic patients are prone to tinea nail, ringworm, ringworm of the hands, feet, and body, which are prone to secondary bacterial infections due to itching and scratching. Early detection, active treatment, and control of blood glucose plasma can help control the infection early.