Fruits provide us with health-enhancing vitamins and phytochemicals as well as fiber, all important components of our diets, and there is no reason why people with diabetes should forego these benefits. However, you may have to be careful about the fruits you choose, how often you eat them and when you eat them. If you take a look at the glycemic index (GI), a measure of how fast carbohydrate foods (which include fruits) are converted in the body to blood glucose, you'll see that there are big differences between fruits. I recommend choosing fruits that rank low on the glycemic index. Low rankings are those that score below 55, intermediate-GI foods score between 55 and 70 and high GI foods score above 70.
For example, some good fruit choices would include an average-sized apple that scores 38; cherries, which score 22; grapefruit (25); an average-sized orange (44); an average-sized pear (38); a plum (39). Intermediate GI fruits include banana (55); cantaloupe (65); mango (55); papaya (58); pineapple (66). High GI fruits include dried dates (103); and canned fruit cocktail (79). How quickly fruit will raise your blood sugar depends on such considerations as whether you eat the fruit after a high-fat meal or drink it as a glass of fruit juice on an empty stomach. You'll also want to consider what your blood-sugar level is when you eat the fruit. If you're monitoring your blood glucose, you should be able to figure out how it responds to eating fruit. It is also important to pay attention to the size of the fruit you eat - choose a small or medium-sized apple over a large one (or eat only half of the large one). A quick and easy measure of the right serving size of fruit is the amount that can comfortably fit in the palm of your hand. Anything bigger than that is too large.
The question is not whether or not you should eat fruit but rather how much and what kinds of fruit you should be eating. A little experimentation can go a long way.
Andrew Weil, M.D.