The relationship between sensor-detected hypoglycemia and patient-reported hypoglycemia in people with type 1 and insulin-treated type 2 diabetes: The Hypo-METRICS study

Objective: Use of continuous glucose monitoring (CGM) has led to greater detection of hypoglycemia, the clinical significance of this is not fully understood. The HypoMETRICS study was designed to investigate the rates and duration of sensor-detected hypoglycemia (SDH) and their relationship with person-reported hypoglycemia (PRH) in people living with type 1 (T1D) and insulin-treated type 2 diabetes (T2D) with prior experience of hypoglycemia. Research Design and Methods: We recruited 276 participants with T1D and 321 with T2D who wore a blinded CGM and recorded PRH in the Hypo-METRICS app over 10-weeks. Rates of SDH <70mg/dl, SDH <54 mg/dl and PRH were expressed as median episodes/week. Episodes of SDH were matched to episodes of PRH that occurred within 1 hour. Results: Median [Interquartile range] rates of hypoglycemia were significantly higher in T1D vs. T2D; for SDH <70 mg/dl (6.5 [3.8-10.4] vs 2.1 [0.8-4.0]), SDH <54 mg/dl (1.2 [0.4-2.5] vs 0.2 [0.0-0.5]) and PRH (3.9 [2.4-5.9] vs 1.1 [0.5-2.0]). Overall, 65% of SDH <70 mg/dl was not associated with PRH, and 43% of PRH had no associated SDH. The median proportion of SDH associated with PRH in T1D was higher for SDH <70 mg/dl (40% vs 22%) and <54 mg/dl (47% vs 25%) than T2D. Conclusion: The novel findings that at least half of CGM hypoglycemia is asymptomatic, even below 54 mg/dl, and many reported symptomatic hypoglycemia episodes happen above 70 mg/dl. In the clinical and research setting these episodes cannot be used interchangeably, and both need to be recorded and addressed.