--although I question whether over 50 years years of age blanketly qualifies as elderly.

I had always though that the A1c was probably a better measure of overall glycemic control anyway, notwithstanding that there are some people with relatively "normal" A1c levels that show hyperglycemic spikes and hypoglycemic crashes on extended glucose tolerance testing. These people usually, of course, have some degree of pre-diabetic metabolic syndrome/insulin resistance anyway (which testing insulin levels during the GTT often reveals), so they would need to be monitored closely in any case.

My own totally unscientific observations have been that A1c levels do tend to trend upward with age, even among my wife's running cohort. As my experience seems to be showing, this can be combated, but it gets tougher.