Glycemic Load is a more accurate way of determining how foods effect blood sugar levels:

The glyemic load is based on the idea that a small serving of a high GI food will have the same kind of effect as a big serving of a low GI food. Foods that are mostly water, for instance, will not cause a sudden rise in your blood sugar even if they have high GI values.

https://www.glycemic-index.org/glycemic-load-chart.html

Generally, a GL of below 10 is considered low GL, 11 - 19 GL is considered average and GL above 20 is considered high GL.

Protein, fat, and fiber help slow down the digestion of carbohydrates. Hence the effect of eating carbs alone is different than with protein/fat.


If blueberries contain something which helps improve your blood sugar levels, that should factor in as well.

"Blueberries ....don’t have adverse effects on blood sugar levels, which may be due to their high content of bioactive compounds.

Test-tube studies suggest that the anthocyanins in blueberries can have beneficial effects on blood sugar control "

This is assuming Blueberries are eaten in SMALL amounts.

https://www.ketosee.com/are-blueberries-keto-net-carb/

Blueberries: Keto Positive Points
-May help control blood sugar levels and lead to smaller insulin spikes.

-Low glycemic load.
Blueberries also have a glycemic load (GL) of 5, which is low. This means they don’t cause sudden spikes in blood sugar. Glycemic load measures how likely the carb content of a single serving of a given food is to raise your blood sugar. The number assigned is obtained by multiplying the carb content of a typical serving of the food by its glycemic index.

Strawberries do even better on the GI and GL than blueberries: 3 GL