Glycemic metrics from continuous glucose monitoring (CGM) can vary within the same individual over time. Understanding this variability is important for accurate clinical interpretation. An analysis published in Diabetic Medicine evaluated intraindividual variability in CGM-derived metrics among people with type 1 diabetes using automated insulin delivery (AID) systems.

The study analyzed CGM data collected over 56 days from 142 individuals using AID systems. Glycemic metrics were calculated across different timeframes. These included four separate 14-day periods and two 28-day periods. The analysis focused on consistency in time in range (TIR) within individuals.

The results showed greater variability with shorter monitoring periods. For 14-day intervals, the 95% limit of agreement for TIR differences was ±13.4%. Nearly 46.5% of paired measurements differed by more than 5% points. When TIR was assessed over 28-day intervals, variability decreased. The limits of agreement narrowed to ±9.0%. A smaller proportion, 27.6%, showed differences greater than 5%.

These findings indicate that a 28-day CGM assessment provides more stable glycemic metrics. Longer monitoring may support a more reliable interpretation of TIR in clinical practice.