One of the limitations of the food insulin index data is that the tests were undertaken over a period of three hours, while protein takes a lot longer to fully digest.
As shown in the chart below (from Andreas Einfeldt / Diet Doctor) simple carbohydrates cause blood sugar to rise and fall quickly, however slower digesting protein causes a rise in blood sugar (in a healthy non-diabetic) between four and six hours after a meal (green line).
One of the challenges for type 1 diabetics is that, even if they limit their carbohydrates, their blood sugar will often spike a number of hours after a high protein meal. And sometimes faster digesting proteins such as protein powder raise the blood sugar much faster than a slow digesting steak.
The image below shows the continuous glucose monitor plot of a type 1 diabetic after a protein shake (46.8g protein and only 5.6g of carbs). Without insulin to blunt the glocogenic effect of the protein, the blood sugar rise from the fast acting protein is not dissimilar to what you would see from carbohydrates.
On the positive side, protein does not spike blood sugar as much as carbohydrate and is therefore easier to manage. Though for type 1 diabetics it is important to be conscious of the amount of protein in the diet and manage it accordingly, particularly if they have their carbohydrate intake dialed in and want to achieve optimal blood sugar control.
Similarly, it’s important for type 2 diabetics and people trying to lose weight via a controlled carbohydrate carbohydrate diet to keep in mind that excess protein, although it might not have a significant effect on their blood sugars, will also raise their insulin levels and work against weight loss or nutritional ketosis.
[next article… is the insulin reaction to protein dose dependent?]
[this post is part of the insulin index series]
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