Mother-law with poor diet

My mother-law (with type 2 diabetes) will go a good part of the day not eating properly, thinking that when she is feeling tired she will be picked up by a piece of candy of something. She often complains that she is tired and little episodes feeling out of sorts (nauseau, tired, weight gain). We are very concerned for her and when she wants to care for my children and driving them on lengthy trips (to take them to see family). We feel that she is developing something really bad and don't know how to help a stubborn old woman who won't even come to terms that she is dealing with a serious disease. She takes insulin on a regular basis, and not controlling her diabetes with diet.
What to do??

[WaveRider]

"...and driving them on lengthy trips (to take them to see family"
And you trust mom driving your kids on lengthy trips?

Not much you can do about getting mom to control her diabetes when she doesn't want to listen nor do anything to help herself. You know that old adage, you can lead a horse to water...