Basically, it means he has too much glucose in his circulatory system for some reason (hyperglycemia). His metabolism is not working properly — so he has too much energy in circulation and it’s not getting into his cells. You need to know what Type of diabetes it is — people are less likely to get Type 1 autoimmunity in their senior years, but it has happened to my relative and a few others I have talked to. Most new adult diagnosis are Type 2, which is insulin resistance — but there’s a few other possible reasons. You need to understand that he will probably take some kind of medication, and also be on some level of carbohydrate reduction. You need to understand what a glucometer is and what normal blood sugar range is (75-95 mg/dL or 4-6 mmol/l), also what an A1c 3-month average is normal (4.6% to 5.5% maybe). People try to control their blood glucose levels to stay healthy. High levels of glucose can cause problems with virtually every part of the body — brain, eyes, skin, heart, kidneys.... The way people try to control this is via food choices, exercise, medication, and lots of testing. People using insulin have to test often to avoid low blood sugars and to gauge how much insulin to take. Beyond that, what do you want to know? It can change a person’s life completely but mostly it is a lot of extra maintenance. Some people do well with it, some do not and suffer from complications after some years of damaging high glucose. It can be expensive and emotionally draining, but can also cause people to learn to be healthier and more able to adjust to life’s problems. All this depends on the person and their support system. Doctors are part of that system, and they are not all equally good at patient care or knowledge.