medwireNews: Glucose variability rises with increasingly insulin-dependent forms of diabetes, report researchers.
Among 376 patients undergoing continuous glucose monitoring (CGM), glucose variability rose with increasing intensity of treatment among the 254 with type 2 diabetes, and was higher still in 122 patients with type 1 diabetes.
Louis Monnier (University of Montpellier, France) and colleagues defined unstable glycemia as a percentage coefficient of variation for glucose (%CV) of 36%. This definition is calculated as the standard deviation of glucose divided by mean glucose, all multiplied by 100, and the researchers say it is more practical than other, more complex definitions of glucose variability, being “easily accessible and computable by any healthcare professional.”
They chose a %CV threshold of 36% because it was the upper limit of the %CV distribution among patients who had type 2 diabetes but were not receiving an insulinotropic agent (ie, they were treated with diet and metformin and/or glitazones). As treatment intensified, more patients fell above this threshold: no patients who were receiving dipeptidyl peptidase 4 inhibitors, but 12.3% of those taking sulfonylureas, and 19.0% of those using insulin (either basal–bolus or basal alone).
And 55.7% of the type 1 diabetes patients fell above the threshold, suggesting to the researchers “that disease progression is reflected in worsening of [glucose variability] compounded by the necessary escalation of treatment.”
The team notes that glucose variability has yet to be directly linked to cardiovascular outcomes, but is associated with hypoglycemia, which in turn is associated with cardiovascular risk. In the current study, the rate of hypoglycemia was markedly higher among patients above the 36% threshold than those under it. Among insulin-dependent type 2 diabetes patients, for example, the number of episodes per patient–day was 0.57 versus 0.06 for those above and below the threshold, respectively.
Writing in Diabetes Care, Monnier and team suggest that unstable glycemia could be underdiagnosed in clinical practice, “especially in patients with type 2 diabetes treated with insulinotropic agents (sulfonylureas) and/or insulin therapy.”
They ask: “Is there an argument in favor of a broader use of CGM data for detecting silent hypoglycemic events in such patients, at least in those who are considered ‘vulnerable’ and prone to hypoglycemia?”
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