Glycemic Variability: Measurement and Utility in Clinical Medicine and Research—One Viewpoint

Abstract

One cannot control average glucose levels unless one firstreducesglycemicvariability! Thissounds intuitively obvious 1,2 and can also be demonstrated rigorously, mathematically. 3 If the mean glucose level were 100mg/dL but the SD were 40mg/dL, one could predict that there would be an unacceptable incidence of severe hypoglycemia even though the mean glucose is in the euglycemic range. Clinicians must understand glycemic variability both qualitatively and quantitatively and endeavor to reduce that variability before trying to reduce the mean level of blood glucose. This applies to blood glucose as measured by self-monitoring of blood glucose (SMBG), laboratory measurements of venous samples or arterial blood, and interstitial glucose as measured by continuous glucose monitoring (CGM). When titrating a medication such as basal insulin, it is essential to know the between-day (within-subject) variability in fasting plasma glucose to be able to set the target glucose level appropriately so that risk of hypoglycemia is at an acceptable level. Unfortunately, these estimates of glycemic variability are rarely obtained. Glycemic variability also serves as one facet of the quality of glycemic control—another reason to quantify gly