Table 1

Baseline characteristics of people with type 1 diabetes and controls with no prior amputation by categories of HbA1c at first inclusion in the National Diabetes Register from 1998 to 2013

Controls
n=182 617
All type 1 diabetes
n=36 577
P value
Women*82 738 (45.3%)16 567 (45.3%)0.97
Age (years)*35.2 (14.6)
n=182 617
35.2 (14.6)
n=36 577
0.79
Age category
 18–34102 427 (56.1%)20 495 (56.0%)
 35–4945 377 (24.8%)9083 (24.8%)
 50–6427 588 (15.1%)5533 (15.1%)
 65+7225 (4.0%)1466 (4.0%)0.72
Born in Sweden158 353 (86.7%)34 028 (93.0%)<0.0001
Education category
 Low38 640 (21.5%)8091 (22.4%)
 Mid92 477 (51.6%)19 378 (53.7%)
 High48 234 (26.9%)8629 (23.9%)<0.0001
Variables in the National Diabetes Register only
HbA1c (mmol/mol, IFCC)66.1 (14.7)
n=36 340
HbA1c (%, NGSP)8.20 (1.35)
n=36 340
Diabetes duration (years)19.9 (14.7)
n=36 577
Insulin method
Injection27 972 (80.3%)
Pump6841 (19.7%)
BMI (kg/m2)25.9 (4.6)
n=35 343
LDL (mmol/L)2.63 (0.82)
n=33 009
Systolic BP (mm Hg)126.1 (15.7)
n=36 121
Diastolic BP (mm Hg)72.6 (9.3)
n=36 121
Smoking4435 (12.3%)
Blood pressure-lowering medication14 171 (39.3%)
Lipid-lowering medication12 978 (35.9%)
eGFR93.5 (31.6)
n=34 328
Albuminuria
Normoalbuminuria26 797 (80.0%)
Microalbuminuria3796 (11.3%)
Macroalbuminuria217 (6.3%)
CKD stage 5794 (2.4%)
Registrations in the inpatient register prior to baseline
Acute myocardial infarction (I21)835 (0.5%)808 (2.2%)<0.0001
Atrial fibrillation (I48)811 (0.4%)215 (0.6%)0.0004
Coronary heart disease (I20–I25)1667 (0.9%)1605 (4.4%)<0.0001
Heart failure (I50)438 (0.2%)491 (1.3%)<0.0001
Valve disease (I05–I09, I34–I36)359 (0.2%)134 (0.4%)<0.0001
Stroke (I61–I64)726 (0.4%)548 (1.5%)<0.0001
Cancer (C00–C97)2093 (1.1%)515 (1.4%)<0.0001
Foot ulcer (circulatory complications) (E10.5, E11.5, E12.5, E13.5, E14.5)17 (0.0%)1349 (3.7%)<0.0001
  • For categorical variables, n (%) is presented. For continuous variables, mean (SD) is presented.

  • *Variables used in the matching process.

  • BMI, body mass index; BP, blood pressure; CKD, chronic kidney disease; eGFR, estimated glomerular filtration rate; HbA1c, hemoglobin A1c; IFCC, International Federation of Clinical Chemistry; LDL, low-density lipoprotein; NGSP, National Glycohemoglobin Standardization Program.