Table 1

Key metrics for CGM data analysis and reporting

CGM metricMeasuresATTD consensus
1Mean glucose√ (calculated)
Severe hypoglycemia*Clinical diagnosis: event requiring assistance (level 3)
Percentage of time in hypoglycemic ranges, mg/dL (mmol/L)
2 Clinically significant/very low/immediate action required<54 (<3.0) (level 2)
3 Alert/low/monitor<70–54 (<3.9–3.0) (level 1)
Percentage of time in target range, mg/dL (mmol/L)
4 Default70–180 (3.9–10.0)
 Secondary70–140 (3.9–7.8)
Percentage of time in hyperglycemic ranges, mg/dL (mmol/L)
5 Alert/elevated/monitor>180 (>10) (level 1)
6 Clinically significant/very elevated/immediate action required>250 (>13.9) (level 2)
Diabetic ketoacidosis*Clinical diagnosis: ketones, acidosis, and usually hyperglycemia (level 3)
Glycemic variability
7 Primary glycemic variabilityCV
  StableCV <36%,
  UnstableCV ≥36%
 Secondary glycemic variabilitySD
8eA1C√ (calculated)
9Three time blocks: sleep, wake, 24 h12:00 a.m.–6:00 a.m., 6:00 a.m.–12:00 a.m., 12 a.m.–12:00 a.m.
Recommended data sufficiency
10 Collection period (minimum no. of weeks)2
11 Percentage of expected CGM readings (minimum percentage)70–80 (10 of 14 days)
12Episodes of hypoglycemia/hyperglycemia (minimum no. of minutes) (with beginning and end of episode defined)15 min
13Area under the curve√ (calculated)
14Risk of hypoglycemia and hyperglycemiaLBGI/HBGI recommended
15Standardized CGM visualization of dataAGP recommended
  • * Severe hypoglycemia (level 3) and diabetic ketoacidosis (level 3) are not key CGM metrics per se. However, these conditions are included in the table because they are important clinical categories that must be assessed and documented.