*Geek Box: Area Under the Curve

*Geek Box: Area Under the Curve

If you read research, you’ll come across the commonly used term ‘area under the curve’, or the ‘AUC’.

Imagine you had a 1-meter deep bucket, and you filled it with a slow tap. If you measured the level of water in the bucket at different time points, you would have the value for each time-point, e.g., 30cm, 60cm, 90cm. But the sides of the bucket in the first 10cm would be exposed to the water for longer, while the bucket is filling.

So, if you wanted to calculate the total exposure of the bucket to water once it is full, you could use a mathematical formula to calculate this value. Rather than just have the concentration of water in the bucket at specific times, you now have the full concentration of the whole bucket over the time it took to fill.

To convert this analogy, the AUC gives you a measure of the total exposure to a compound in circulation. For example, let’s say you measure blood glucose in the 2-hours after a meal, every 30mins. This gives you 4 values. Each of those values alone doesn’t give you a measure of the total exposure to blood glucose over that timeframe, because they are single values taken when in fact blood glucose was elevated and changing minute-to-minute.

Therefore, to capture the full exposure over the entire 2-hour period, AUC calculations can be used for different measures, whether glucose, insulin, free-fatty acids, or perhaps a supplement. This provides a more informative picture of the level of exposure to a compound in circulation, whether a nutrient, hormone, or other metabolite or measure.