Blood glucose levels are not constant in ther human body even in physiological status. It fluctuates depending on food intake, exercise, psychological and other factors. Normally it fluctuates between 3.9 to 7.5 mmol/l and in fasting in the standard conditions it does not exceed even more narrow range 3.9 to 5.5 mmol/l. Fluctuations are more pronounced in patient with diabetes. Hyperglycemia is a common and basic pathology in diabetes, however, antidiabetic drug often cause hypoglycemia, both increasing the range for glucose fluctuations. The level of glucose fluctuation is called glycemic variability (GV). Glycemic variability is now a favorite target of scientific research in dia-betology. Increased glycemic variability is associated with hypoglycemia, possibly may contribute to chronic dia-betes complications and negatively influences quality of life of diabetic patients. Last but not least, thanks to the new technology of continuous glucose monitoring, we can better describe and measure it. Finally, glycemic variability emerges as a potentially important therapeutical target.Key words: continuous glucose monitoring - glycemic variability - insulin pump - sensor augmented pump.