The Diabetes Control and Complications Trial (DCCT) asked the question, “Do efforts to control blood glucose impact the development or progression of the long-term complications of diabetes?”
In this prospective, randomized, multicenter study involving 1,441 patients with type 1 diabetes followed for 6½ years, the effects of intensive insulin therapy vs conventional insulin therapy on early microvascular and neurologic complications were compared. Intensively treated patients received either insulin pump therapy or three or more injections of insulin daily. Adjustments in treatment were determined by the results of frequent home blood glucose monitoring.
A1c levels reached a nadir in the intensively treated group in 6 months. The difference in the average A1c between the two groups was statistically significant (P<0.001) and was maintained after baseline (average, 9.1% and 7.2% for the conventional and intensive therapy groups, respectively).
This slide summarizes the effects of improved blood glucose control on retinopathy, nephropathy, and neuropathy. Intensive therapy reduced the risk for:
development of retinopathy by 63% (P<=0.002; 95% confidence interval [CI], 52% to 71%)
nephropathy, determined by albuminuria (excretion rate >=300 mg/24 hr), by 54% (P<0.04; 95% CI, 19% to 74%)
clinical neuropathy by 60% (P<=0.002; 95% CI, 38% to 74%).
Diabetes Control and Complications Trial Research Group. N Engl J Med. 1993;329:977-986.
Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Research Group. N Engl J Med. 2000;342:381-389.