Actually, what you should be trying to do is eat less than a third of your total calorie intake as fat. This is different from what you’re stating. For instance, I just looked at the nutrition panel of the margarine in my fridge. Calories per serving: 90. Calories from fat per serving: 90. In other words, 100% of the calories in that margarine comes from fat. Does this mean that someone who’s watching fat intake can’t eat this? No, it just means that this person needs to be aware of how much margarine to use.
As for your real question, go to a doctor or dietician, and ask for a diabetic guideline. Or just pick up a nutrition booklet, they’re all around. Incidentally, the fats that you want to reduce are of animal origin, and tropical oils. MOST vegetable oils are good for you. Olive oil is particularly good for you. Tropical oils (palm, coconut, etc.) are not as good for you.
Also, beware of what I call the “Snackwell delusion”. While Snackwells are not the only culprits, many lowfat foods will loudly proclaim that they’re lowfat…while not mentioning that they’re very high in sugar. In some cases, the “lowfat” variety of foods is just as high in calories as the regular version, you’re just getting your calories in sugar rather than in fat.