A recent study answers the question for once and for all: long-term control of hyperglycemia over 30 years dramatically cuts the rate of complications in people with type 1 diabetes (T1DM).
The study is from the researchers who did the Diabetes Control and Complications Trial (DCCT) back in the 1980's and early 1990's. In that study, 1441 people with T1DM were randomized to either intensive glucose control or standard care. Back in those days, intensive glucose control meant multiple injections or an insulin pump, 4 blood glucose tests a day, and frequent followup by a diabetes team. Standard care was one-shot-a-day of insulin, and urine testing. The DCCT results were pretty impressive over the ten years that patients were studied: intensive glucose control cut the rate of eye, kidney, and nerve complications -- there was a sixty-two percent reduction in relative risk of diabetic retinopathy (eye disease), fifty-six percent less progression of kidney disease, and sixty percent less progression of neuropathy (nerve damage), in the intensively-treated group of patients.
But, one might argue, that's over a period of "only" ten years. What about longer time-frames, such as oh, maybe thirty years? Would the results continue to be so striking?
In a word, yes.
The recent study, Modern-Day Clinical Course of Type 1 Diabetes Mellitus After 30 Years' Duration: The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications and Pittsburgh Epidemiology of Diabetes Complications Experience (1983-2005) evaluated the DCCT patients as well as other patients who were diagnosed in the years from 1950 to 1980.
After 30 years of diabetes, DCCT participants assigned to intensive glucose control had about half the rate of eye damage compared to those assigned to standard care (21 percent vs. 50 percent). They also had lower rates of kidney damage (9 percent vs. 25 percent) and cardiovascular disease events (9 percent vs. 14 percent) compared to those receiving standard care.
Another comment by one of the researchers: "After 30 years of diabetes, fewer than 1 percent of those receiving intensive glucose control in the DCCT had significantly impaired vision, kidney failure, or needed a limb amputation due to diabetes." (There's more discussion about this study at Intensive Glucose Control Halves Complications of Longstanding Type 1 Diabetes Study Finds Improved Long-Term Outlook).
The only question I have is not about these results in T1DM, but rather whether the same results would occur in patients with T2DM. There has been recent concern about forcing BG too low perhaps causing increased mortality in patients who have both T2DM and heart disease (see ACCORD and ADVANCE again), but overall, it's my guess that if someone is able to analyze outcomes for intensively-treated T2DM, that they will show similar results.