BACKGROUNDCardiovascular disease causes severe morbidity and mortality in type 1 diabetes, although the specific risk factors and whether chronic hyperglycemia has a role are unknown. We examined the progression of carotid intima-media thickness, a measure of atherosclerosis, in a population with type 1 diabetes.METHODSAs part of the Epidemiology of Diabetes Interventions and Complications (EDIC) study, the long-term follow-up of the Diabetes Control and Complications Trial (DCCT), 1229 patients with type 1 diabetes underwent B-mode ultrasonography of the internal and common carotid arteries in 1994-1996 and again in 1998-2000. We assessed the intima-media thickness in 611 subjects who had been randomly assigned to receive conventional diabetes treatment during the DCCT and in 618 who had been assigned to receive intensive diabetes treatment.RESULTSAt year 1 of the EDIC study, the carotid intima-media thickness was similar to that in an age- and sex-matched nondiabetic population. After six years, the intima-media thickness was significantly greater in the diabetic patients than in the controls. The mean progression of the intima-media thickness was significantly less in the group that had received intensive therapy during the DCCT than in the group that had received conventional therapy (progression of the intima-media thickness of the common carotid artery, 0.032 vs. 0.046 mm; P=0.01; and progression of the combined intima-media thickness of the common and internal carotid arteries, -0.155 vs. 0.007; P=0.02) after adjustment for other risk factors. Progression of carotid intima-media thickness was associated with age, and the EDIC base-line systolic blood pressure, smoking, the ratio of low-density lipoprotein to high-density lipoprotein cholesterol, and urinary albumin excretion rate and with the mean glycosylated hemoglobin value during the mean duration (6.5 years) of the DCCT.CONCLUSIONSIntensive therapy during the DCCT resulted in decreased progression of intima-media thickness six years after the end of the trial.

Context The Diabetes Control and Complications Trial (DCCT) demonstrated the benefits of intensive treatment of diabetes in reducing glycemic levels and slowing the progression of diabetic nephropathy. The DCCT cohort has been examined annually for another 8 years as part of the follow-up Epidemiology of Diabetes Interventions and Complications (EDIC) study. During the EDIC study, glycemic levels no longer differed substantially between the 2 original treatment groups.Objective To determine the long-term effects of intensive vs conventional diabetes treatment during the DCCT on kidney function during the EDIC study.Design, Setting, and Participants Observational study begun in 1993 (following DCCT closeout) in 28 medical centers in the United States and Canada. Participants were 1349 (of 1375) EDIC volunteers who had kidney evaluation at years 7 or 8.Main Outcome Measures Development of microalbuminuria, clinical-grade albuminuria, hypertension, or increase in serum creatinine level.Results Results were analyzed by intention-to-treat analyses, comparing the 2 original DCCT treatment groups. New cases of microalbuminuria occurred during the EDIC study in 39 (6.8%) of the participants originally assigned to the intensive-treatment group vs 87 (15.8%) of those assigned to the conventional-treatment group, for a 59% (95% confidence interval [CI], 39%-73%) reduction in odds, adjusted for baseline values, compared with a 59% (95% Cl, 36%-74%) reduction at the end of the DCCT (P<.001 for both comparisons). New cases of clinical albuminuria occurred in 9 (1.4%) of the participants in the original intensive-treatment group vs 59 (9.4%) of those in the original conventional-treatment group, representing an 84% reduction in odds (95% Cl, 67%-92%), compared with a reduction of 57% (95% Cl, -1% to +81%) at the end of the DCCT. Fewer cases of hypertension (prevalence at year 8, 29.9% vs 40.3%; P<.001) developed in the original intensive-treatment group. Significantly fewer participants reached a serum creatinine level of 2 mg/dL or greater in the intensive-treatment vs the conventional-treatment group (5 vs 19, P=.004), but there were no differences in mean log clearance values. Although small numbers of patients required dialysis and/or transplantation, fewer patients experienced either of these outcomes in the intensive group (4 vs 7, P=36).Conclusions The persistent beneficial effects on albumin excretion and the reduced incidence of hypertension 7 to 8 years after the end of the DCCT suggest that previous intensive treatment of diabetes with near-normal glycemia during the DCCT has an extended benefit in delaying progression of diabetic nephropathy.

OBJECTIVE - The Diabetes Control and Complications Trial (DCCT) demonstrated the powerful impact of glycemic control on the early manifestations of microvascular complications. Contemporary prospective data on the evolution of macrovascular and late microvascular complications of type 1 diabetes are limited. The Epidemiology of Diabetes Interventions and Complications (EDIC) study is a multicenter, longitudinal, observational study designed to use the well-characterized DCCT cohort of >1,400 patients to determine the long-term effects of prior separation of glycemic levels on micro- and macrovascular outcomes.RESEARCH DESIGN AND METHODS - Using a standardized annual history and physical examination, 28 EDIC clinical centers that were DCCT clinics will follow the EDIC cohort for 10 years. Annual evaluation also includes resting electrocardiogram, Doppler ultrasound measurements of ankle/arm blood pressure, and screening for nephropathy At regular intervals, a timed 4-h urine is collected, lipid profiles are obtained, and stereoscopic fundus photographs are taken. In addition, dual B-mode Doppler ultrasound scans of the common and internal carotid arteries will be performed at years 1 and 6 and at study end.RESULTS - Written informed consent was obtained from 96% of the DCCT subjects. The participants, compared with nonparticipants, tended to have better glycemic control at the completion of the DCCT and were more likely to have their diabetes care provided by DCCT personnel. The EDIC baseline measurement stratified by sex delineates multiple cardiovascular disease risk factor differences such as age (older in men), waist-to-hip ratio (higher in men), HDL cholesterol (lower in men), hypertension (more prevalent in men), and maximum intimal-medial thickness of common and internal carotid arteries (thicker in men). Of the original conventional treatment group, 69% have changed to continuous subcutaneous insulin infusion or multiple daily injections. Although the mean HbA(1c) difference between the intensive and conventional treatment groups narrowed at EDIC years 1 and 2, HbA(1c) remained significantly lower in the intensive group. Of all expected clinic visits, 95% were completed, and the quality of EDIC data is very similar to that observed in the DCCT.CONCLUSIONS - Although obvious problems exist in extended follow-up studies of completed clinical trials, these are balanced by the value of continued systematic observation of the DCCT cohort. In contrast to other epidemiologic studies, EDIC will provide 1) definitive data on type 1 as distinct from type 2 diabetes; 2) reliance on prospective rather than on cross-sectional analysis; 3) long-term followup in a large population; 4) consistent use of objective, reliable measures of outcomes and glycemia; and 5) observation of patients from before the onset of complications.

OBJECTIVE - To describe the methods used to implement intensive and conventional therapies in the Diabetes Control and Complications Trial (DCCT) and the metabolic results that occurred with the different treatment regimens.RESEARCH DESIGN AND METHODS - The DCCT was a controlled clinical trial that demonstrated the beneficial effect of intensive therapy on the long-term complications of insulin-dependent diabetes mellitus (IDDM). A total of 1,441 volunteers with IDDM, aged 13-39, from 29 centers in the U.S. and Canada, were randomly assigned to conventional or intensive diabetes therapy. Intensive therapy, which used multiple daily injections (MDI) of insulin (greater than or equal to 3 injections/day) or continuous subcutaneous insulin infusion (CSII), was implemented by a team that included diabetes nurses, dietitians, behavioral experts, and diabetologists. Volunteers in the intensive treatment group could use MDI or CSII, based on patient and clinic preference, and could switch between therapies over the course of the study. The volunteers were followed for a mean of 6.5 years (range 3-9 years).RESULTS - A detailed analysis of implementation of the two treatments indicates that intensive and conventional treatment subjects adhered to their respective insulin injection regimens >97% of the time. Adherence to other elements of intensive treatment was similarly high and resulted in median HbA(1c) values between 6.7 and 7.2, compared with 8.7-9.2 with conventional therapy, over the course of the study. Severe hypoglycemia occurred three times more often in intensively treated subjects. Although subjects on intensive treatment were not randomly assigned to MDI or CSII, we compared those subjects who used either of these methods for greater than or equal to 90% of the study time. CSII-treated patients maintained a mean HbA(1c) of 6.8 vs. 7.0 in MDI-treated subjects during the trial (P < 0.05). The frequency of hypoglycemia with coma and seizure and diabetic ketoacidosis was modestly higher with CSII than with MDI.CONCLUSIONS - Intensive therapy was implemented successfully in the DCCT. The detailed description herein will serve to facilitate translation of the DCCT results to the clinical setting.

Objective: To determine the magnitude of the decrease in the risk of retinopathy progression observed with intensive treatment and its relationship to baseline retinopathy severity and duration of follow-up.Design: Randomized clinical trial, with 3 to 9 years of follow-up.Setting and Patients: Between 1983 and 1989, 29 centers enrolled 1441 patients with insulin-dependent diabetes mellitus aged 13 to 39 years, including 726 patients with no retinopathy and a duration of diabetes of 1 to 5 years (primary prevention cohort) and 715 patients with very mild to moderate nonproliferative diabetic retinopathy and a duration of diabetes of 1 to 15 years (secondary intervention cohort). Ninety-five percent of all scheduled examinations were completed.Interventions: Intensive treatment consisted of the administration of insulin at least three times a day by injection or pump, with doses adjusted based on self-blood glucose monitoring and with the goal of normoglycemia. Conventional treatment consisted of one or two daily insulin injections.Outcome Measures: Change between baseline and follow-up visits on the Early Treatment Diabetic Retinopathy Study retinopathy severity scale, assessed with masked gradings of stereoscopic color fundus photographs obtained every 6 months.Results: Cumulative 8.5-year rates of retinopathy progression by three or more steps at two consecutive visits were 54.1% with conventional treatment and 11.5% with intensive treatment in the primary prevention cohort and 49.2% and 17.1% in the secondary intervention cohort. At the 6- and 12-month visits, a small adverse effect of intensive treatment was noted (''early worsening''), followed by a beneficial effect that increased in magnitude with time. Beyond 3.5 years of follow-up, the risk of progression was five or more times lower with intensive treatment than With conventional treatment. Once progression occurred, subsequent recovery was at lease two times more likely with intensive treatment than with conventional treatment. Treatment effects were similar in all baseline retinopathy severity subgroups.Conclusion: The results of the Diabetes Control and Complications Trial strongly support the recommendation that most patients with insulin-dependent diabetes mellitus use intensive treatment, aiming for levels of glycemia as close to the nondiabetic range as is safely possible.