Your sister probably consumed other carbohydrates in amounts too large for her pancreas to handle. As a general rule most adults over thirty should begin limiting their intake of carbohydrates. Diabetes is more than just an over consumption of sugars and starches. Other factors like genetics and physical conditioning also play a part.
I see a bunch of posters jumping to conclusions.
Yeah, I still eat a good amount of carbs, but I usually only eat 2 meals a day and only one of them is a large meal so I don’t have too many issues.