Persistent hyperglycemia caused by diabetes can damage many systems throughout the body and lead to a variety of complications, the common complications are: Metabolic disorders: the most common is the imbalance of water-electrolyte metabolism, even because of the hypertonicity of the blood and lead to brain tissue dehydration, hypertonic coma, and can also lead to ketoacidosis due to the accumulation of ketone bodies. Infectious diseases: The accumulation of blood sugar leads to the body being prone to infections on the one hand, and also makes it difficult for wounds to heal on the other hand, so diabetics are prone to septic infections such as boils and carbuncles, as well as fungal and tuberculosis infections. Chronic complications: Continuous hyperglycemia will lead to microvascular lesions, gradual hardening of the walls, narrowing of the canal diameters, and even occlusion resulting in interruption of blood flow, which eventually leads to diabetic nephropathy and diabetic retinopathy. Peripheral nerve complications are mainly symmetrical sensory abnormalities, mostly due to nerve endings damage and vascular occlusion of nerve trophoblastic nerves. Autonomic nervous system complications are mainly manifested by abnormalities in basic regulation of digestion, sleep, and sweating. Diabetic foot: It is the most serious and expensive complication of diabetes, mostly due to neurovascular damage resulting in poor blood supply, difficult wound healing and secondary infection, and limited treatment, eventually progressing to lead to amputation or death. In summary, the danger of diabetes is quite extensive, complications throughout the system, early detection and early treatment, control of blood sugar to avoid complications is the key.