The Beneficial Effects of Earlier Versus Later Implementation of Intensive Therapy in Type 1 Diabetes

OBJECTIVE The principal aim is to estimate the benefits of earlier versus later implementation of intensive therapy in type 1 diabetes with respect to the long-term risks of progression of a renal (microvascular) and cardiovascular (macrovascular) complication in the Epidemiology of Diabetes Interventions and Complications (EDIC) study. RESEARCH DESIGN AND METHODS Cox proportional hazards regression models estimated the 20-year cumulative incidence (absolute risk) and the 20-year relative risk of cardiovascular disease (CVD) and reduced estimated glomerular filtration rate (eGFR) over the first 20 years of EDIC follow-up as a function of the mean HbA1c. RESULTS A hypothetical patient treated earlier with 10 years of intensive therapy and a mean HbA1c of 7% (53 mmol/mol) followed by 10 years with a mean of 9% (75 mmol/mol) would have a 33% reduction in the risk of CVD and a 52% reduction in reduced eGFR compared with a patient with a mean HbA1c of 9% (75 mmol/mol) over the first 10 years followed by later intensive therapy over 10 years with an HbA1c of 7% (53 mmol/mol). Despite both patients having the same average glycemic exposure over the 20 years, the patient with the lower HbA1c over the first 10 years had a lower risk of progression of complications over the 20 years than the patient who had the higher value initially. CONCLUSIONS While implementation of intensive therapy at any time in type 1 diabetes will be beneficial, within the 20-year period modeled, earlier relative to later implementation is associated with a greater reduction in the risks of kidney and cardiovascular complications.