Table 1.
Frequently used measurements of glycemic variability.
| Glycemic variability measurement | Calculation definition | Strengths | Limitations | Author (publication date) |
|---|---|---|---|---|
| Standard deviation (SD) | SD of all glucose concentrations in a distribution. | Simple, classical statistical method. | Does not account for skewed distributions or outliers. | Rodbard D (2009)25; Hirsch IB & Brownlee M (2005)2; Rodbard D (2018)18 |
| Percent coefficient of variation (%CV) | (SD÷mean) × 100 SD and mean value of all glucose concentrations in a distribution. |
Simple, classical statistical method. Incorporates both the SD and mean value of a distribution. |
Does not account for skewed distributions or outliers. | Rodbard D (2009)25; Hirsch IB & Brownlee M (2005)2; Rodbard D (2018)18 |
| Mean amplitude of glycemic excursions (MAGE) | Average amplitude of upstrokes or downstrokes with a magnitude > 1 SD above the mean value for all glucose concentrations. | Account for physiological fluctuations due to events throughout the day. e.g. meals, exercise |
Less efficient to calculate than SD, while providing similar outcomes. | Service FJ et al. (1970)22; Service FJ & Nelson RL (1980)23; Service et al. (1987)24 |
| Continuous overlapping net glycemic action over n-h (CONGA-n) | The SD of the difference between 2 glucose concentrations obtained exactly n h apart. | Potential to address a variety of clinical questions. CONGA-1 to CONGA-4 valid and reliable when accounting for corresponding times between different activities. |
Validity and reliability decrease once time frame > 4 h in a controlled setting. | McDonnell CM et al. (2005)26; Nathan DM et al. (2008)27; Kuenen JC et al. (2011)28 |
| Mean of daily differences (MODD) | Mean of absolute differences between glucose values obtained at the same time of day on 2 consecutive days under standardized conditions. Mean of absolute differences in glucose values over > 2 days between any value and the value exactly 24 h later. |
Describes between-day variability. Ability to permit use of data from > 2 unstructured days. |
Originally defined for 2 consecutive days assuming similar meals, activities, and therapy on both days. | Service FJ & Nelson RL (1980)23; Service et al. (1987)24 |
Table 1 provides frequently used measurements of glycemic variability, which includes the calculation definition of each glycemic variability measurement with further consideration for strengths and limitations of each glycemic variability measurement.
SD = standard deviation; %CV = percentage coefficient of variation; MAGE = mean amplitude of glycemic excursions; CONGA-n = continuous overlapping net glycemic action over n-h; MODD = mean of daily differences.