It can be a true story. Juvenile diabetes can remain hidden for years without notice. The same case happened in a family in India and I know them very well. We all played together when we were young and nobody ever had a smallest doubt on her condition. My Mom told that when that girl was 18 something she suddenly collapsed one day and immediately went into coma. Only after this everybody including her family members came to know abt her diabetes. Well, she died within 3 days.
So, I think this story also can be a true story.

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