Table 1.
Commonly used GV indices.
| GV Index | Definition or Calculation Formula | Comments |
|---|---|---|
| Glucose SD | A measure of dispersion of measured glucose values around the mean. | Very familiar to physicians and easy to calculate [26]. |
| Glucose CV | (SD)/(mean glucose)ǀ×ǀ100 [3] | A CV of ≤36% is recommended in patients with diabetes [27]. More robust than glucose SD because of taking into consideration the mean glucose values [3]. |
| TIR | Percentage of time spent with the blood glucose levels within the range of 3.9–10 mmol/L | In general, it is recommended to be maintained above 70% [3,15]. Should be determined based on individual needs and risk of hypoglycaemia. |
| TAR | Percentage of time spent with blood glucose levels above 10 mmol/L [3] | Recommended targets differ depending on individual patients’ situations, but in general for patients with T2DM, a TAR > 10 mmol/L (level 1 hyperglycaemia) of <25%, and a TAR > 13.9 mmol/L (level 2 hyperglycaemia) of <5% is recommended [4]. |
| TBR | Percentage of time spent with blood glucose levels below 3.9 mmol/L [3] | Recommended targets differ depending on individual patients’ situations, but in general for patients with T2DM, a TBR < 3.9 mmol/L (level 1 hypoglycaemia) of <4% and a TBR < 3.0 mmol/L (level 2 hypoglycaemia) of <1% is recommended [28]. |
| MAGE | A measure of glucose fluctuations that exceed 1 SD from the mean (high and low) [3] | Takes into account peaks and nadirs of glucose levels not just the numbers of fluctuations [18]. Capable of identifying large glucose excursions. |
| MDD | Based on calculation of absolute differences between two glucose values measured 24 h apart [26] | A metric for estimating the between-day GV. |
| CONGA | SD of the differences of glucose readings for a defined period of time [26] | Measures within-day GV. |
| MAG | The sum of absolute differences among consecutively measured glucose values divided by the duration of time over which the measurements were conducted [29] | This is a good indicator of dramatic GV in critically ill patients, for example in intensive care units [30]. |
| GMI | It is an estimated HbA1c based on the average glucose levels measured by CGM [3] | Needs glucose values for a consecutive period of 10–14 days for calculation [31]. |
CGM, continuous glucose monitoring; CV, coefficient of variation; CONGA, Continuous Overlapping Net Glycaemic Action; GMI, Glucose Management Indicator; GV, glycaemic variability; MAG, Mean Absolute Glucose; MAGE, Mean Amplitude of Glycaemic Excursions; MDD, Mean of Daily Differences; SD, standard deviation; TAR, Time Above Range; TBR, Time Below Range; TIR, Time in Range.