Glycemia Risk Index bests time in range in assessing hypoglycemia for adults with diabetes
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Key takeaways:
- Adults with a time below range of 4% or higher had increases in Glycemia Risk Index despite rising time in range.
- Glycemia Risk Index increases as time below range increases, regardless of time in range.
The new continuous glucose monitoring metric Glycemia Risk Index better assesses hypoglycemia risk than time in range, according to study data.
As Healio previously reported, the Glycemia Risk Index (GRI) was released in 2022 to provide a metric that better captures the time a person with diabetes spends in hypoglycemia or hyperglycemia. New findings published in Diabetes Technology & Therapeutics used CGM tracings from a group of adults with diabetes to examine how GRI compares with time in range.
“To the best of our knowledge, this is the first study to compare the GRI with time in range and other composite metrics in clinical practice, using both cross-sectional and longitudinal analyses,” Jae Hyeon Kim, MD, PhD, clinical assistant professor in the department of endocrinology and metabolism at Samsung Medical Center, Sungkyunkwan University School of Medicine in Seoul, South Korea, and colleagues wrote. “As GRI is not yet commonly used in clinical practice, our study validates its usefulness for assessing glycemia quality. We also confirmed that the GRI can be applied to Asian patients.”
Kim and colleagues collected 90-day CGM tracings from 194 insulin-treated adults with diabetes at Samsung Medical Center from 2019 to 2022 (mean age, 43.9 years; 43% men). All participants used the Dexcom G5 or G6 CGM. Up to four 90-day CGM tracings were collected for each adult for a total of 524 CGM tracings. CGM metrics were obtained from ambulatory glucose profiles. GRI and its hypoglycemia and hyperglycemia components were calculated, with a higher GRI score indicating worse glycemic control. The study compared GRI with time in range as well as three other composite CGM metrics.
Of the study population, 98.5% had type 1 diabetes. The mean time in range was 68.6% and the mean GRI score was 36.6 of a possible 100. Adults with a time below range of 4% or more had a higher GRI than those with a time below range of less than 4% (38.3 vs. 31.2; P = .032), despite also having a higher time in range (71.7% vs. 67.7%; P = .031). In linear regression analysis, GRI was negatively correlated with time in range (r = –0.974; P < .001) and positively correlated with coefficient of variation (r = 0.683; P < .001).
CGM tracings were grouped into quartiles according to time in range, with the lowest quartile having a time in range of 50% to 59% and the highest having a time in range of 80% or more. GRI increased as time below range increased in all time-in-range groups. Time in range did not differ by time below range quartile.
In longitudinal analysis, CGM tracings were paired to analyze the change in metrics after change in time below range improved. Among 48 pairs where time below range improved, GRI improved from 40.6 to 37 (P = .003), whereas there was no change in time in range. Among 23 pairs where time below range did not improve, there was no change in GRI or time in range. When time above range improved, both GRI and time in range improved (P < .001 for both).
“Time in range is a useful CGM metric for assessing glycemic quality; however, it does not weigh hypoglycemia as more important than hyperglycemia, as do experienced clinicians,” the researchers wrote. “In contrast, GRI can assess both hypoglycemia and hyperglycemia by assigning more weight to hypoglycemia.”
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