*Geek Box: Measures of Blood Glucose and Terminology
So, let’s spell some terms out here so you’re on clear terms of what we’re talking about. Let’s start with glycaemia, which simply means the blood glucose level, thus postprandial glycaemia means the levels of glucose in the blood after a meal.
Then we have glycated haemoglobin A1c [HbA1c], a marker for longer-term blood glucose regulation over the period of the previous 3-months and is expressed as a percentage. Currently, 6.5% is considered the threshold for a diagnosis of T2D, and the range of 6.0–6.4% is considered ‘high-risk’ according to World Health Organisation guidelines.
There is also a concept important for the present study, known by the broad definition of glycaemic variability [GV]. In simple terms, GV is the swings in blood glucose levels that occur throughout the day. GV includes the elevations in blood glucose that occur after a meal, the time spent with high or low blood glucose levels, and the difference in blood glucose responses at the same time of day, on different days.
There are several measures of GV, but the present study used the mean amplitude of glycaemic excursion [MAGE], which is a measure of the glucose excursions in response to meals that exceed 1 standard deviation from the average response. It also calculated the mean of daily difference [MODD], which expresses how much the average variation in glucose on one day compares to the next [i.e., a low MODD indicates consistent glucose variability from day to day, a good thing!].
Finally, the homeostatic model of insulin resistance [HOMA-IR] is calculated from fasting insulin and glucose measures, based on higher fasting insulin levels responding, in a feedback loop, to higher fasting glucose levels, indicating peripheral insulin resistance to glucose uptake.