What are the clinical, quality-of-life, and cost consequences of 30 years of excellent vs. poor glycemic control in type 1 diabetes?

OBJECTIVE: The Diabetes Control and Complications Trial (DCCT) demonstrated that intensive therapy for type 1 diabetes delayed the development of microvascular and neuropathic complications compared to conventional therapy. At the end of DCCT, all participants were trained in intensive therapy, care was transferred to community providers, and the difference in HbA1c between treatment groups narrowed and disappeared. Our objective was to describe the outcomes and the quality-of-life and costs associated with those outcomes in participants who maintained excellent vs. poor glycemic control over 30 years.

RESEARCH DESIGN AND METHODS: We assessed the incidence of retinopathy, nephropathy, neuropathy, cardiovascular disease, acute metabolic complications, death, quality-of-life, and costs in the tertile of DCCT intensive therapy participants who achieved a mean updated HbA1c of <7.2% (55 mmol/mol) and the tertile of DCCT conventional therapy participants (n = 240) who achieved a mean updated HbA1c of >8.8% (73 mmol/mol) over 30 years.

RESULTS: Thirty years of excellent vs. poor glycemic control substantially reduced the incidence of retinopathy requiring laser therapy (5% vs. 45%), end-stage renal disease (0% vs. 5%), clinical neuropathy (15% vs. 50%), myocardial infarction (3% vs. 5%), stroke (0.4% vs. 2%), and death (6% vs. 20%). It also resulted in a gain of ~1.62 quality-adjusted life-years and averted ~$90,900 in costs of complications per participant.

CONCLUSIONS: Thirty years of excellent vs. poor glycemic control for T1DM can substantially reduce the incidence of complications, comorbidities, and death, improve quality-of-life, and reduce costs. These estimates represent the benefits that may be achieved with excellent glycemic control.