Data on carotid intima-media thickness and lipoprotein subclasses in type 1 diabetes from the Diabetes Control and Complications Trial and the Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC)

Type 1 diabetes (T1DM) is associated with increased risk of macrovascular complications. We examined longitudinal associations of serum conventional lipids and nuclear magnetic resonance (NMR)-determined lipoprotein subclasses with carotid intima-media thickness (IMT) in adults with T1DM (n=455) enrolled in the Diabetes Control and Complications Trial (DCCT). Data on serum lipids and lipoproteins were collected at DCCT baseline (1983–89) and were correlated with common and internal carotid IMT determined by ultrasonography during the observational follow-up of the DCCT, the Epidemiology of Diabetes Interventions and Complications (EDIC) study, at EDIC ‘Year 1’ (199–1996) and EDIC ‘Year 6’ (1998–2000). This article contains data on the associations of DCCT baseline lipoprotein profiles (NMR-based VLDL & chylomicrons, IDL/LDL and HDL subclasses and ‘conventional’ total, LDL-, HDL-, non-HDL-cholesterol and triglycerides) with carotid IMT at EDIC Years 1 and 6, stratified by gender. The data are supplemental to our original research article describing detailed associations of DCCT baseline lipids and lipoprotein profiles with EDIC Year 12 carotid IMT (Basu et al. in press) [1].

a b s t r a c t Type 1 diabetes (T1DM) is associated with increased risk of macrovascular complications. We examined longitudinal associations of serum conventional lipids and nuclear magnetic resonance (NMR)-determined lipoprotein subclasses with carotid intimamedia thickness (IMT) in adults with T1DM (n ¼455) enrolled in the Diabetes Control and Complications Trial (DCCT). Data on serum lipids and lipoproteins were collected at DCCT baseline (1983-89) and were correlated with common and internal carotid IMT determined by ultrasonography during the observational Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/dib Carotid intima-media thickness Type 1 diabetes follow-up of the DCCT, the Epidemiology of Diabetes Interventions and Complications (EDIC) study, at EDIC ' Year 1' (199-1996) and EDIC ' Year 6' (1998Year 6' ( -2000. This article contains data on the associations of DCCT baseline lipoprotein profiles (NMR-based VLDL & chylomicrons, IDL/LDL and HDL subclasses and 'conventional' total, LDL-, HDL-, non-HDL-cholesterol and triglycerides) with carotid IMT at EDIC Years 1 and 6, stratified by gender. The  May facilitate new therapies to target lipids and lipoprotein classes significantly associated with vascular events in diabetes.

Data
The Diabetes Control and Complications Trial (DCCT) examined the effects of intensive diabetes management on the development and progression of diabetic retinopathy [2]. The cohort comprised 1441 T1DM patients aged 13-39 years who were free of overt cardiovascular disease (CVD) at enrollment in 1983-89. In 1994, the Epidemiology of Diabetes Interventions and Complications Trial (EDIC), a longitudinal observational phase of DCCT was initiated to assess the long-term effects of the DCCT intervention on cardiovascular and related complications [3]. Carotid IMT data were obtained at EDIC 'Years ' 1 (1994-1996), 6 (1998-2000), and 12 (2004)(2005)(2006). In addition to conventional lipids, nuclear magnetic resonance (NMR)-determined lipoprotein subclasses have been predictive of CVD in some T1DM studies [4][5][6], and were analyzed in this cohort to examine associations with a surrogate of CVD: common and internal carotid IMT.
The baseline characteristics of the participants have been described previously [1]. Table 1 shows data on the associations of DCCT baseline standard lipid profiles and NMRLSP with common carotid IMT in men and women at EDIC Years 1 and 6. Generally the data reveal positive associations of conventional LDL-cholesterol and NMR-based total IDL/LDL with IMT, and inverse associations of NMR-based large and medium VLDL subclasses, medium HDL and HDL particle size with IMT, most marked in men. Table 2 shows data on the associations of DCCT baseline standard lipid profiles and NMR-LSP with internal carotid IMT in men and women at EDIC Years 1 and 6. Generally there are positive Table 1 DCCT baseline lipoprotein profiles vs. common carotid IMT-EDIC Years 1 and 6 (standardized linear regression coefficients a ).

Variables
Men ( associations of conventional total, LDL-and non-HDL cholesterol levels with IMT in both men and women, and of NMR-based total IDL/LDL, small LDL and HDL (small)-subclasses with IMT in men only. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) provides access to the raw data from the DCCT/EDIC study through the NIDDK Central Repository (https://www.niddkre pository.org/home/). This website includes information regarding the data sets that are available, and details of the data request, review, and approval process.

Study subjects
The original DCCT cohort comprised 1441 T1DM participants aged 13-39 years at study entry (1983)(1984)(1985)(1986)(1987)(1988)(1989). They had no dyslipidemia or hypertension and were randomly assigned to conventional  (n ¼730) or intensive (n ¼711) diabetes treatment [2]. The data included in this article are derived from a sub-set of DCCT participants with available common and internal carotid IMT measurements at EDIC Years 1 and 6. The study was approved by the Institutional Review Boards of MUSC, University of Oklahoma Health Sciences Center (OUHSC), and all participating DCCT/EDIC centers, and written informed consent was obtained from all subjects.

Ultrasonography and image analysis
Common and internal carotid IMT measurements in EDIC have previously been described in detail [7]. Reliability measures for IMT readers at EDIC Years 1 and 6 have been reported previously [8]. In the current sub-study, we examined the longitudinal associations between lipoprotein profiles at DCCT entry (1983-89) and common and internal carotid IMT at EDIC Years 1 and 6.

NMR Lipoprotein subclass analysis
NMR-LSP was determined in first-thaw serum specimens (250 mL) using a 400-MHz proton NMR analyzer at LipoScience Inc. (Raleigh, NC, USA) as described [9]. Lipoprotein subclasses were expressed as molar particle concentrations and defined by particle diameter: VLDL subclasses (large: . Average VLDL, LDL, and HDL particle sizes (nm) were determined by weighting the relative mass percentage of each subclass by its diameter.

DCCT baseline conventional lipid profiles, HbA 1c , and other clinical measurements
Total cholesterol, triglyceride, and HDL-C levels were determined using previously reported enzymatic methods [10]. LDL-C was estimated according to the Friedewald equation. HbA 1c was measured by high-performance ion exchange liquid chromatography [11].

Statistical analysis
Multiple regression analyses were performed to examine correlations of conventional lipids and NMR-LSP at DCCT baseline with common and internal carotid IMT at EDIC Years 1 and 6, stratified by gender. Each lipid/lipoprotein measure was included as an independent variable in the linear model simultaneous with a fixed group of covariates that were measured at DCCT baseline: diabetes duration, smoking (yes/no), DCCT treatment group, body mass index (BMI), urinary albumin excretion rate (AER), and HbA 1c , statin use and ultrasound imaging device. Two-tailed p o0.05 was considered to be statistically significant. Data were analyzed using SAS/STAT software (Version 9.2; SAS Institute Inc., Cary, NC).