In 1993, the Diabetes Control and Complications Trial's (DCCT’s) demonstration that strict control of blood glucose to near-normal levels during an average of 6.5 years in subjects with type 1 diabetes significantly reduced the progression of retinopathy as well as other chronic microvascular complications of the disease was among the most important results from a randomized controlled clinical trial in medical history.1 This was followed, a few years later, by the results of another randomized controlled trial, the United Kingdom Prospective Diabetes Study, which demonstrated the same result for subjects with type 2 diabetes.2 Together, these 2 trials, now classics of medicine, definitively answered the long-troubling question as to whether maintaining blood glucose level in the near-normal range really does produce beneficial long-term results in diabetic patients.
Frank RN. Metabolic Memory in Diabetes Is True Long-term Memory. Arch Ophthalmol. 2009;127(3):330-331. doi:10.1001/archophthalmol.2008.607