Background. Type 2 diabetes mellitus (DM2) is one of the most common and severe diseases of our time, leading not only to disability, but also to premature death of patients. In 2021, 6.7 million people with diabetes died [1]. One of the reasons for high mortality is the late detection of DM2 and its complications, which begin to develop already at the stage of prediabetes. Active screening, timely detection and treatment of any disorders of carbohydrate metabolism at the earliest stages will slow down the rate of conversion of prediabetes to DM2, as well as timely diagnose and treat complications of hyperglycemia.
Objective. Optimization of the algorithm for selective screening, diagnosis and treatment in the early stages of carbohydrate metabolism disorders among individuals with risk factors for developing DM2 and to evaluation of the effectiveness of drug correction of prediabetes.
Methods. To assess carbohydrate metabolism, fasting venous plasma glucose (FVPG) was examined at the screening stage, and for further diagnosis, a two-hour oral glucose tolerance test (OGTT) with 75 g of anhydrous glucose was performed. Plasma glucose concentration was determined in the laboratory of the Tambov Central District Hospital using a digital photoelectric calorimeter «APEL AP-101» and a biochemical automatic analyzer CA - 270 «Furuno». Blood samples were collected into tubes with a glycolysis inhibitor (sodium fluoride), coded with a gray cap. Blood samples were prepared according to a unified preanalytical procedure (International Organization for Standardization ISO, 2000).
Results. Continuous screening of carbohydrate metabolism disorders in compliance with all rules for preanalytical preparation of blood samples was carried out among 1136 apparently healthy individuals. Subsequent diagnosis of the state of carbohydrate metabolism was required in 531 (46.7%) of 1136 examined, after which various categories of dysglycemia were confirmed in 210 (39.5%) of 531 individuals. The need for mandatory diagnosis of the state of carbohydrate metabolism in individuals with fasting venous plasma glucose levels ≥5.6≤6.0 mmol/l and the presence of metabolic syndrome and/or DM2 risk factors has been confirmed. Early administration of drug prevention of DM2 in combination with lifestyle changes to normalize glycemia in people with prediabetes has proven to be safe and effective during an active three-year follow-up period. Subsequent regular use of metformin at a daily dose of 500 mg for 10 years in 83.3% of patients prevented the development of any disorders of carbohydrate metabolism, including DM2.
Conclusion. Compliance with the rules of preanalytical preparation of blood samples is required both when screening for carbohydrate metabolism disorders and their subsequent diagnosis. Compliance with the recommendations of the International Diabetes Federation (IDF) on expanding the indications for diagnostic OGTT contributes to the early detection of various disorders of carbohydrate metabolism. Metformin can be considered the main drug of choice as a means of drug prevention of DM2 at the stage of prediabetes; its safety and effectiveness has been demonstrated by the results of a long-term follow-up period.

Keywords: oral glucose tolerance test (OGTT), fasting venous plasma glucose, impaired fasting glucose, impaired glucose tolerance, type 2 diabetes mellitus, prediabetes, metformin, screening, prevention