My father is a type 2 diabetic. He has always had a bad diet, but even since his diabetes came on about 20 years ago he has only really cared about preventing hypoglycemia (low blood sugar) instead of hyperglycemia (high).
This makes sense, since with low blood sugar you can see his discomfort, so the immediate physical effects make him consume some sugar in order to avoid the unwanted blood sugar levels.
However, his attitude to high blood sugar is very blasé. He will eat whatever he wants (lots of sugary things), and generally inject more insulin when the blood sugar is a bit too high. From looking into it, high blood sugar seems to be more detrimental in the long term to health, so I have been unable to find anything with which I might be able to convince my father to reduce his sugary habits with. He is an old man, and unsurprisingly, does not consider the long term to be very important.
What are the negative effects caused by short hyperglycemia (as my father will inject insulin once the blood sugar is too high)?