All foods containing carbohydrates affect blood sugar level, not just those with sugar. Have you noticed that diabetics avoid rice — rice has a carb content. However, it is the amount of carbohydrate you eat and not the type that has the biggest influence on blood sugar levels.
Because of this, people with diabetes can treat all carbohydrate-containing foods (including fruit) the same when meal planning. Too much of any carbohydrate at a given meal will probably raise your blood sugar higher than you would like. Therefore, a big part of diabetes meal planning is devoted to “carb budgeting” and managing the carbohydrates intake. You should work with your dietitian and doctor in order to determine how much carbohydrate you need.
In carb budgeting you can include fruit in your meals. For instance if you have a 60 gram allowance of carbohydrate for breakfast and you decide you want to have a banana with your upma, adjust your carbohydrate servings accordingly. A 5-inch banana contains roughly 15 grams of carbohydrates, which leaves you with 45 grams left for the upma.
So by all means go ahead and eat fruit. Just remember that all fruits are not created the same and calories and carbohydrates differ from all types of fruit. Try and choose fresh fruit. Fruit juice is devoid of fiber and can have added sugar.