Table 1

Measures of glycemia and glycemic variability in the DCCT cohort at baseline, at 1 year of follow-up, and over all visits (N = 1,441); incident cases of retinopathy and microalbuminuria and prevalent cases of CAN over all visits

BaselineYear 1All visits
Measure of average glucose, median (quartiles 1, 3), rSD*
 Within-day mean blood glucose (mg/dL)223.1 (172.2, 282.1)177.1 (134.8, 231.5)182.7 (139.7, 241.7)
81.571.775.6
 Longitudinal mean of the profile mean glucose (mg/dL)223.1 (172.2, 282.1)183.4 (148.4, 232.3)182.0 (149.1, 229.6)
81.562.259.7
 Longitudinal mean HbA1c (%)8.8 (7.9, 10.1)7.6 (6.9, 8.9)7.9 (7.0, 9.1)
1.61.51.6
 Longitudinal mean HbA1c (mmol/mol)72.7 (62.8, 86.9)59.6 (51.9, 73.8)62.8 (53.0, 76.0)
17.916.217.0
Measures of glucose variability, median (quartiles 1, 3), rSD*
 Within-day standard deviation (mg/dL)77.2 (60.2, 98.7)72.0 (52.6, 92.2)74.6 (55.2, 97.7)
28.529.431.5
 Within-day MAGE (mg/dL)163.8 (117.0, 214.5)143.0 (103.0, 201.5)154.5 (109.0, 213.5)
72.373.077.5
 Within-day M-value96.9 (56.1, 154.5)53.2 (27.1, 103.3)61.68 (31.82, 114.3)
72.956.561.2
 Longitudinal mean MAGE (mg/dL)163.8 (117.0, 214.5)150.4 (122.3, 183.3)158.6 (133.4, 187.2)
72.345.239.9
 Longitudinal mean M-value96.9 (56.1,154.5)58.3 (36.0, 97.9)71.14 (45.64, 112.1)
72.945.949.3
 Total variance within and between days (mg/dL)26,165.7 (3,770.6, 9,893.2)6,093.9 (4,239.0, 8,709.4)7,129.1 (4,902.4, 10,000.4)
4,538.73,314.03,779.2
 Between-day variance (mg/dL)21,465.1 (700.5, 3,013.9)1,980.6 (1,040.7, 3,605.6)
1,714.91,901.3
 Pooled within-day variance (mg/dL)26,165.7 (3,770.6, 9,893.2)5,694.5 (3,960.8, 7,983.8)6,213.1 (4,491.4, 8,438.9)
4,538.72,982.22,926.3
Incident and prevalent outcomes
 Retinopathy (N = 1,441), incidence, n (%)271 (18.8)
 Microalbuminuria (N = 1,284), incidence, n (%)118 (9.2)
 CAN (N = 1,375), prevalence at years 2, 4, 6, and 8 (n)49, 79, 60, 24
  • *All analyses of glucose-based values are based on multiply imputed data sets. Values for the quartiles of each measure are calculated using all imputations. The SDs are calculated using Rubin’s variance formula (20) averaged over imputations (except for the longitudinal variances).

  • †For the longitudinal variances, the rSD is a robust estimator of the SD obtained as 0.7413 × (quartile 3 − quartile 1) from a randomly selected imputation.

  • ‡Incident retinopathy: ≥3-step change on the ETDRS scale at a 6-month visit in the full cohort (N = 1,441); incident microalbuminuria: AER ≥30 mg/24 h on two successive annual visits among the 1,284 subjects with AER <30 mg/24 h at baseline; prevalent CAN as described in Research Design and Methods among the 1,375 subjects without CAN at baseline.