We all know (I hope) that it's a good idea to keep our blood glucose (BG) levels as close to normal as possible. Deciding how close involves a lot of factors, balancing good BG control with enjoyment of life, economics, family preferences, and so on.
But it seems that more and more things are affected by our BG levels, which should give us an incentive to put a little more effort into good control.
It's been known for a long time that keeping BG levels close to normal can reduce the risk of the complications I call "the O'Pathy sisters": retinopathy, neuropathy, and nephropathy. But there's more recent evidence that high BG levels can contribute to Alzheimer's disease. It's known that people with type 2 diabetes are at increased risk of Alzheimer's.
Glycation apparently affects an enzyme involved in Alzheimer's, and "a glycation pattern similar to that observed in AD brain homogenates could be reproduced by incubating [the enzyme] MIF with glucose." You can see the full text here.
Note that this research is complex and preliminary. So it's not something you should lose sleep over. However, it's one more hint that controlling BG levels is important.
Another recent study links poor diabetes control to heart disease. Note that the headline links heart disease to diabetes. A more accurate headline would have linked it to poorly controlled diabetes, as the text says, "When diabetes is poorly managed, your blood sugar goes up and the amount of this protein goes down." Too little of the protein in question contributes to atherosclerosis.
You can see the abstract of the study here.
Finally, a third study showed that tighter glycemic control in type 2 patients with heart failure for just 4 months helped to preserve muscle strength and lean body mass. This was not what most of us would call tight control, as the final hemoglobin A1c level was 7.6, but that was lower than the 8.4 in the controls. The free full text of that paper can be found here.
These are just a few studies, but as more studies of other functions are carried out, it's likely that the effect of good control will be duplicated.
Good control isn't always easy in today's world, but it's worth the sacrifices.