Diabetes mellitus is a group of metabolic diseases affecting carbohydrate, lipid, and protein metabolism. This pathology has a long history, and it was considered a disease of the kidneys until the middle of the 19th century. Descriptions have been found in Egyptian papyri, in ancient Indian and Chinese medical literature, in the writings of ancient Greek and Arab doctors. Aretaeus of Cappadocia gave the first accurate description of the disease, coining the term “diabetes”. Thomas Willis first differentiated diabetes from other causes of polyuria by the sweet taste of urine. Matthew Dobson proved the presence of glucose in urine by evaporation. Claude Bernard demonstrated that hyperglycemia contributes to glucosuria. This is how the concept of the renal threshold appeared. In domestic practice, the term "renal threshold" was introduced by endocrinologist V.G. Baranov. The development of qualitative tests for determining glucose in the urine, the creation of test strips and glucometers has significantly improved the quality of life of patients with diabetes. The current stage of development of glucometry includes the determination of fasting plasma glucose, postprandial glycemia, glycated hemoglobin, as well as continuous glucose monitoring. Continuous glucose monitoring systems make it possible to estimate the time in target range, show the rate of rise or fall of glucose levels. It affects the rate and degree of carbohydrate metabolism compensation and allows for maximum control of the disease.