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. In connection with the research into 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. Several studies have described the relation of glycemic variability to macrovascular complications of diabetes, still its relation to microvascular complications remains unclear. This overview summarizes the recent findings in the field of glycemic variability and its possible association with retinopathy, nephropathy and neuropathy.Key words: type 1 and 2 diabetes mellitus - glycemic variability - microvascular complications - HbA1c - variability.