The glycemic index is a scientific representation which shows how carbohydrate-containing foods are ranked. Foods that have a high score on the charts rapidly raise blood sugar, and foods that score low raise blood sugar slowly. According to the chart, low ranking-GI foods score below 55, intermediate foods rank between 55 and 70 and high GI foods score above 70. Fresh raspberries, blackberries, strawberries and blueberries all have scores below 40.
If a person has diabetes, the key to keeping their blood sugar under control is to both, consume foods with low glycemic indexes and to use portion control. Thanks to the low-carbohydrate density of berries diabetics could safely eat them. For diabetics, good serving sizes for berries are as such:
Strawberries = 1¼-cup serving
Blueberries = 3/4 cup
Blackberries = 3/4 cup
Raspberries = 1 cup
Fruits like berries contain fructose, a natural sugar that doesn’t require insulin to be metabolized. Strive to consume at least two servings of berries each day.
source: http://alkalinevalleyfoods.com