Rationale. The key purpose of modern glucose meters is to ensure regular self-monitoring of glucose level when receiving outpatient management, provided that fair diabetes compensation is achieved. Although glucose meters are not intended for assessing the glucose level in severe metabolic disorders (ketosis, ketoacidosis), since these conditions have a negative effect on device accuracy, in actual life a patient (or a physician) can face a situation when a glucose meter is the only tool for evaluating carbohydrate metabolism disorders. Objective. To evaluate clinical accuracy of Satellite Express PKG-03 glucose meter in measuring the glucose level in patients with type 1 and 2 diabetes mellitus (DM) receiving insulin therapy when the disease course is complicated by ketosis or ketoacidosis. Material and methods. Capillary blood was simultaneously collected in two groups of patients receiving insulin therapy from the same drop to evaluate the glucose blood level using the Satellite Express glucose meter and a SUPER GL laboratory analyzer of glucose and lactate levels. Acid-base imbalance was the key criterion for distributing patients into groups: no disorders were detected in group 1 patients, while group 2 patients had ketosis or ketoacidosis. The results were evaluated using the Clarke error grid. Results. Comparative analysis of blood samples collected from 77 patients showed that all deviations in glucose level indices measured using the Satellite Express glucose meter from the reference values belonged to zones A (the clinically valid values) and B (safe deviations) in patients without acid-base imbalance. In patients hospitalized for ketosis and ketoacidosis (group 2), the deviations from the reference values lay in zones A and B in 97%, while lying on the boundary between zones B and C only in 3%. Conclusion. The Satellite Express glucose meter provided acceptable diagnostic accuracy in patients with ketosis and ketoacidosis.