Oana Patricia Zaharia DCCT/EDIC (observational) trial has followed the patients in who participated in the DCCT trial (interventional).

some of the reports can be found at this link Article Intensive Diabetes Therapy and Glomerular Filtration Rate in...

Article Modern-Day Clinical Course of Type 1 Diabetes Mellitus After...

Since DM is a disease in which a vital nutrient and fuel for metabolism can’t be taken out of the blood and it’s accumulation there produces toxicity, I would look at tracking two processes; a) thé toxicity of sugar deprivation to cellular collective tissues function and to b) the toxic effect of their accumulation in the blood stream. Eventually, high blood sugar does go out into the tissue, even if only in leak form. But what kind of debilitated processing machinery it meets when it finally crosses over and what it does to that debilitated tissue Seems worthy of far greater study. It seems weird that knowing, for example what hyperglycemia does to Red Cells we no longer have available except possibly only in Salt Lake City the means to study whole blood viscosity. That's Only one example of a critical indiquant of red cell rigidity from glycocylation that we can no longer look at in the way we look at serum viscosity. This is just one tiny issue of many!