Table 1.

Summary of patient characteristics and data quality measures. (1) Data presented as mean ± SD. (B) Data presented as median (IQR).

Variable	Entire cohort (n = 1195)	Without microalbuminuria (n = 1023)	With microalbuminuria (n = 172)
(A) Patient characteristics
Sex (% male)	53%	53%	55%
Race (%)
Caucasians	88.4%	88%	90.7%
African-American	7.6%	8.1%	4.7%
Other	4%	3.9%	4.6%
Age at T1D diagnosis (yr)	9.1 ± 3.9	9.0 ± 3.9	9.2 ± 3.4
Duration of T1D (yr)	5.7 ± 3.5	5.9 ± 3.6	4.6 ± 3.1 *
Mean-A1c (NGSP %)	8.8 ± 1.3	8.8 ± 1.3	8.9 ± 1.3
(IFCC mmol/mol)	73.1 ± 14.1	73.0 ± 14.0	73.9 ± 14.7
SD-A1c (NGSP%)	1.67 ± 0.88	1.66 ± 0.86	1.72 ± 0.96
(IFCC mmol/mol)	18.25 ± 9.62	18.14 ± 9.40	18.80 ± 10.49
Age at event or censoring (yr)	14.7 ± 3.5	14.9 ± 3.6	13.8 ± 2.5**
(B) Data quality measures
No. of HbA1c per patient	14 (8–21)	14 (9–22)	12 (6.5–19)*
No. of microalbumin measures per patient	3 (2–5)	3 (2–5)	2 (1–5)*
Year of T1D diagnosis	2001 (1996–1904)	2001 (1997–1904)	1997 (1994–1902) **

T1d, type 1 diabetes; IQR, interquartile range; SD, standard deviation; NGSP, national glycohemoglobin standardization program; IFCC, international federation of clinical chemistry.

^*p < 0.0001,

^**p = 0.0003 when comparing patients with and those without microalbuminuria group.