GV metric | Definition | Clinical implications of GV metric^{*} | Normal reference range (2 SD around mean) |
---|---|---|---|

SD | The amount of variation or dispersion of a data set. The SD of the data set is the square root of its variance. | Variation measure most familiar to clinicians and easy to calculate | SD_{T} 10–26 mg/dL^{†} |

At least eight subtypes of SD: the three most commonly used are 1) overall (total) SD, SD_{T} (SD of all data, all days); 2) within-day SD, SD_{W} (average of SD for each day); and 3) between-day SD, SD_{dm} (SD of the daily means of each day) | Most accurate if values are “normally distributed around the mean,” which is often not the case | ||

%CV | The extent of variability in relation to the mean of the population | Less influenced when comparing data sets with widely different mean glucose values (or HbA_{1c}) | 19–25%^{†} |

100 × SD/mean of the observations | Possibly the “best” single research measure to compare GV over time or between data sets | ||

IQR | The spread of values 25% above and 25% below the median, sometimes called the middle fifty | Likely the “best” metric for visualizing GV around the median glucose curve | 13–29 mg/dL^{†} |

Plotting the IQR (around the median glucose curve) on a modal day glucose profile makes it is easy to spot what time of day has the most GV and needs attention | |||

Mean amplitude of glycemic excursions | Average of all blood glucose excursions or swings (peak to trough) that are greater than 1 SD of all measures for a given glucose profile | Most common measure of glucose spikes, swings, or excursions as opposed to glucose dispersion | 41 and 48 mg/dL^{#} (results from day 1 and 2 for one normal individual using CGM for 48 h) |

Used for many years; can be applied to SMBG or CGM data | |||

Continuous overall net glycemic action (1–24 h) | Intraday (within-day) glycemic variation | No clear benefit of these measures compared with the four more commonly used measures listed above | Few normal studies |

CONGA (1–24 h) | The standard deviation of the differences of glucose readings for a defined period of hours | ||

Mean of daily differences | Interday (between-day) glycemic variation | ||

The absolute value of the difference between glucose values taken on two consecutive days at the same time | |||

Mean absolute difference | Mean absolute difference of consecutive blood glucose values derived from SMBG data performed five times per 24 h | ||

Mean absolute glucose | The summed differences between sequential 7-point SMBG profiles per 24 h divided by the time in hours between the first and last blood glucose measurement |