Lower HbA1c has sustained benefit in lowering kidney disease risk

A review of patients with type 1 diabetes shows that 10 years of intensively controlled diabetes lowers the risk of diabetes complications decades later.
Between 1983 and 1993, 1,441 patients with type 1 diabetes took part in a groundbreaking trial to quantify how much of a difference keeping diabetes well controlled would make to the chances of developing common diabetic complications such as retinal, kidney and nerve disease.
The trial was called the Diabetes Control and Complications Trial (DCCT). Participants were randomly assigned to achieve either standard control or intensive control. Standard control involved no challenging targets, but to avoid symptoms of too high or too low blood sugar levels. Intensive control aimed towards achieving an HbA1c of as close 6% (42 mmol/mol) as possible.
The results were conclusive, the intensively treated patients benefited from a 50% lower risk of kidney disease, 60% lower risk of neuropathy and 76% lower risk of retinopathy.
After the DCCT trial finished, the group that had been intensively treated for 10 years of the DCCT study were allowed to manage their diabetes without needing to achieve such tight control. All participants that took part in the study were invited to take part in a further study, the EDIC (Epidemiology of Diabetes Interventions and Complications) study which continued to monitor the two groups that had taken part in the DCCT. Within the EDIC study, there was no significant difference in terms of average HbA1c between the two groups.
Whilst the intensive group had largely stopped treating their diabetes so intensively since 1993, the results of the follow up showed that the 10 years of tight blood glucose control had greatly reduced the risk of kidney disease 18 years after the DCCT study finished.
An earlier stage of kidney disease is marked by the appearance of small amounts of protein in the urine (microalbuminuria) and later stages are marked by larger amounts of protein in the urine (macroalbuminuria). When the DCCT and EDIC study participants were reviewed, those that had intensively managed their diabetes for the original 10 years had 45% reduced risk of the earlier stage of kidney disease and a 61% reduced risk of the later stages of kidney disease after 18 years of follow up.
The message from the follow up is that if you can safely control your type 1 diabetes well for many years, the benefits of a lower risk of complications will endure for many years into the future.