Vascular complications of diabetes result from long lasting unsatisfactory glycemic control. We usually assess glycemic control based on the value of glycated hemoglobin HbA1c. The glycated hemoglobin test, however, says nothing about short-term glycemic fluctuations. Recently, continuous monitoring of glycemia has enabled us an in-depth assessment of changes in glucose concentrations, called glycemic variability. Together with the research of short-term glycemic variability, also the study of long-term fluctuations in glycemic control based on HbA1c variability has now intensified. Glycemic variability may be related to oxidation stress, endothelial dysfunction and inflammation, the factors traditionally associated with vascular damage. This overview summarizes the recent findings in the field of glycemic variability and its possible association with microvascular complications in patients with type 1 and type 2 diabetes.Key words: glycemic variability, HbA1c variability, microvascular complications, type 1 and type 2 diabetes mellitus.