Posted Apr 24 , 2017 05:09 PM

Toward Defining the Threshold Between Low and High Glucose Variability in Diabetes

Monnier L, et al. Diabetes Care 2016 Online Ahead of Print, December 30th

What were the findings (excerpted from the Abstract)?

The objective of this study was to define the threshold for excess glucose variability (GV), one of the main features of dysglycemia in diabetes. A total of 376 persons with diabetes investigated at the University Hospital of Montpellier (Montpellier, France) underwent continuous glucose monitoring. Participants with type 2 diabetes were divided into several groups: groups 1, 2a, 2b, and 3 (n = 82, 28, 65, and 79, respectively) according to treatment: 1) diet and/or insulin sensitizers alone; 2) oral therapy including an insulinotropic agent, dipeptidyl peptidase 4 inhibitors (group 2a), or sulfonylureas (group 2b); or 3) insulin. Group 4 included 122 persons with type 1 diabetes. Percentage coefficient of variation for glucose (%CV = [(SD of glucose)/(mean glucose)] X 100) and frequencies of hypoglycemia (interstitial glucose <56 mg/dL [3.1 mmol/L) were computed. Percent CVs increased significantly from group 1 (18.1%) to group 4 (37.2%). In group 1, the upper limit of %CV, which served as reference for defining excess of GV, was 36%. Percentages of patients with %CVs above this threshold in groups 2a, 2b, 3, and 4 were 0, 12.3, 19.0, and 55.7%, respectively. Hypoglycemia was more frequent in group 2b and groups 3 and 4 when subjects with a %CV >36% were compared with those with %CV <36%.

Why is this important?

Glycemic variability has been evaluated in many different settings using many different measures. While once, controversial vis-à-vis its importance, there is general consensus that it is a significant contributor to diabetes complications (Gorst C, et al. Diabetes Care 2015;38:,2354-2369). One issue with glycemic variability is defining what degree of variability is clinically significant. The authors of this study chose to define significance narrowly as the likelihood of hypoglycemia. In this regard, a percent coefficient of variation (%CV) of 36% appears to be a suitable threshold to distinguish between stable and unstable glycemia in diabetes because beyond this limit the frequency of hypoglycemia is significantly increased, especially in insulin-treated subjects. This study is welcome as it begins to define the “difference that makes a difference” in one domain, and hopefully additional studies of glycemic variability related to micro- and macrovascular complications will be forthcoming! Are you currently checking on the glycemic variability of your patients on various therapies? Are you using %CV or another index? How do you use the numbers in managing your patients?

Read the Abstract: