TOPLINE

In patients with type 1 diabetes (T1D), continuous glucose monitoring (CGM) hypoglycemic and glycemic variability metrics were associated with the risk for severe hypoglycemia independent of A1c in a pooled analysis. In addition, time in range (TIR) and glycemic variability provided additional information on the risk for diabetic ketoacidosis (DKA) beyond A1c.

METHODOLOGY

• Although A1c remains strongly linked to clinical outcomes, it misses short-term glucose swings, and few studies have thoroughly examined whether newer CGM metrics reveal risks for severe hypoglycemia and DKA that A1c alone overlooks.
• Researchers pooled individual-level data from 1550 patients (median age, 18 years; 53% women) with T1D across 10 studies (nine randomized trials and one observational study).
• CGM metrics, including the TIR of 70-180 mg/dL, time above range (TAR) > 180 and > 250 mg/dL, time below range (TBR) < 70 and < 54 mg/dL, sensor mean glucose, SD, percent coefficient of variation (%CV), and CGM-defined hypoglycemic and hyperglycemic episodes, were calculated from a 14-day baseline period.
• Primary outcomes were incident severe hypoglycemia and DKA after day 14 of the baseline visit.
• The median follow-up duration was 113 days.

TAKEAWAY

• During follow-up, 65 severe hypoglycemia events and 163 DKA events occurred.
• Higher TBR < 70 mg/dL was associated with severe hypoglycemia independent of A1c (hazard ratio [HR] per 1-SD increase, 1.52; 95% CI, 1.29-1.79), as was higher TBR < 54 mg/dL (HR per 1-SD increase, 1.42; 95% CI, 1.24-1.62).
• Greater glycemic variability — measured as SD (HR, 2.21; 95% CI, 1.58-3.08) and %CV (HR, 2.11; 95% CI, 1.69-2.65) — was associated with the risk for severe hypoglycemia independent of A1c; the weekly rate of CGM-defined hypoglycemic episodes also showed significant associations.
• Higher TIR was linked to a lower risk for DKA, whereas higher sensor mean glucose levels, SD, %CV, TAR, and weekly rates of hyperglycemic episodes were linked to a higher risk, and after adjusting for A1c, TIR (HR per 1-SD increase, 0.76; 95% CI, 0.60-0.97) and SD (HR, 1.52; 95% CI, 1.16-2.00) remained independently associated with the risk for DKA.

IN PRACTICE

“[The study] findings highlight the value of CGM for risk assessment and its complementary nature to [A1c] in monitoring T1D,” the authors of the study wrote.

SOURCE

The study was led by Elizabeth Selvin, Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore. It was published online in Diabetes Care.

LIMITATIONS

The number of severe hypoglycemia and DKA events remained limited. The included studies differed in follow-up duration and participant characteristics, which may have introduced residual heterogeneity. Different CGM systems can produce different glycemic metrics for the same individual.

DISCLOSURES

One author disclosed receiving support from a Merit Award from the American Heart Association and a National Institutes of Health or National Heart, Lung, and Blood Institute grant. Another author disclosed receiving support from a National Institute of Diabetes and Digestive and Kidney Diseases career development award.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.