Characteristics of the individuals with type 1 diabetes (T1D) and their controls for the three studies
| Variable | Original study | National analysis 1 | National analysis 2 | |||
| Controls | T1D | Controls | T1D | Controls | T1D | |
| N | 2573 (100%) | 862 (100%) | 114 790 (100%) | 38 523 (100%) | 223 995 (100%) | 77 392 (100%) |
| Admission (within 28 days) | 120 (5%) | 86 (10%) | 3735 (3%) | 3422 (9%) | 8665 (4%) | 8263 (11%) |
| Age (years) | 39.0 (17.0) | 39.4 (17.4) | 40.3 (18.0) | 40.5 (18.2) | 38.6 (18.3) | 38.9 (18.4) |
| Sex (is male) | 1349 (52.4%) | 454 (52.7%) | 58 290 (50.8%) | 19 655 (51.0%) | 117 304 (52.4%) | 40 722 (52.6%) |
| Townsend score (higher is more deprived) | 0.9 (3.7) | 0.9 (3.6) | −0.1 (3.6) | −0.2 (3.5) | 0.0 (3.6) | −0.1 (3.5) |
| Townsend quintile (higher is more deprived) | ||||||
| 1 (least deprived) | 447 (17%) | 135 (16%) | 24 210 (21%) | 7889 (21%) | 46 237 (21%) | 15 612 (20%) |
| 2 | 364 (14%) | 126 (15%) | 23 891 (21%) | 8335 (22%) | 46 173 (21%) | 16 372 (21%) |
| 3 | 430 (17%) | 150 (17%) | 22 092 (19%) | 7686 (20%) | 42 955 (19%) | 15 548 (20%) |
| 4 | 564 (22%) | 202 (23%) | 21 294 (19%) | 7340 (19%) | 42 809 (19%) | 15 136 (20%) |
| 5 (most deprived) | 768 (30%) | 249 (29%) | 23 303 (20%) | 7273 (19%) | 45 821 (21%) | 14 724 (19%) |
| Latest BMI value | 27.9 (6.2) | 27.2 (5.8) | 27.9 (6.7) | 27.4 (6.1) | 27.6 (6.8) | 27.0 (6.1) |
| Latest LDL cholesterol value | 2.9 (0.9) | 2.5 (1.0) | 2.9 (0.9) | 2.4 (0.9) | 2.9 (0.9) | 2.4 (0.9) |
| Latest HDL cholesterol value | 1.4 (0.4) | 1.4 (0.4) | 1.4 (0.4) | 1.5 (0.5) | 1.4 (0.4) | 1.5 (0.4) |
| Latest eGFR value | 82.3 (13.8) | 80.5 (18.1) | 81.1 (13.7) | 80.3 (19.4) | 80.6 (14.2) | 79.7 (20.3) |
| Latest HbA1c value | 34.5 (8.8) | 67.6 (22.7) | 36.5 (4.2) | 66.8 (18.8) | 36.4 (4.2) | 67.3 (19.2) |
| Latest total cholesterol value | 5.0 (1.0) | 4.6 (1.1) | 5.0 (1.1) | 4.5 (1.1) | 5.0 (1.1) | 4.5 (1.1) |
| Current smoking status | ||||||
| Non-smoker | 1800 (70%) | 593 (69%) | 98 551 (86%) | 32 924 (86%) | 191 091 (85%) | 65 661 (85%) |
| Smoker | 773 (30%) | 269 (31%) | 16 239 (14%) | 5599 (15%) | 32 904 (15%) | 11 731 (15%) |
| Patient has asthma | 430 (17%) | 149 (17%) | 19 453 (17%) | 6583 (17%) | 35 532 (16%) | 12 782 (17%) |
| Patient has COPD | 41 (2%) | 21 (2%) | 1659 (1%) | 599 (2%) | 2940 (1%) | 1112 (1%) |
| Patient has severe mental illness | 41 (2%) | 21 (2%) | 921 (1%) | 387 (1%) | 1757 (1%) | 761 (1%) |
| Patient has hypertension | 257 (10%) | 197 (23%) | 11 965 (10%) | 8580 (22%) | 20 990 (9%) | 15 869 (21%) |
| Patient is on ACEI | 178 (7%) | 210 (24%) | 5590 (5%) | 6805 (18%) | 9716 (4%) | 12 537 (16%) |
| Patient is on aspirin | 52 (2%) | 91 (11%) | 2417 (2%) | 3351 (9%) | 4098 (2%) | 6182 (8%) |
| Patient is on clopidogrel | 27 (1%) | 37 (4%) | 1038 (1%) | 1215 (3%) | 1922 (1%) | 2361 (3%) |
| Patient is on metformin | 9 (0%) | 117 (14%) | 224 (0%) | 4133 (11%) | 347 (0%) | 7418 (10%) |
| Hospital length of stay (days) | 3.8 (8.6) | 5.2 (8.2) | 2.8 (8.2) | 4.0 (9.2) | 2.6 (9.1) | 3.8 (10.3) |
| Ethnicity | ||||||
| White | 1731 (67%) | 650 (75%) | 95 942 (84%) | 34 755 (90%) | 185 136 (83%) | 69 364 (90%) |
| Asian | 334 (13%) | 73 (9%) | 8977 (8%) | 1701 (4%) | 17 233 (8%) | 3373 (4%) |
| Black | 54 (2%) | 26 (3%) | 3113 (3%) | 869 (2%) | 6649 (3%) | 1950 (3%) |
| Mixed | 46 (2%) | 10 (1%) | 2128 (2%) | 610 (2%) | 4524 (2%) | 1346 (2%) |
| Other | 91 (4%) | 33 (4%) | 2497 (2%) | 455 (1%) | 5325 (2%) | 969 (1%) |
| Unknown | 317 (12%) | 70 (8%) | 2133 (2%) | 133 (0%) | 5128 (2%) | 390 (1%) |
‘Original study’ is the original published study from Greater Manchester with data from 1 January 2020 up to 31 May 2021. ‘National analysis 1’ is the first replication analysis using COVID-19 test data from the primary care data feed. ‘National analysis 2’ is the second replication analysis using the Second-Generation Surveillance System for the COVID-19 test results. The national analysis was on data from 1 January 2020 to 31 December 2022. Values are presented as either ‘mean (SD)’ or ‘count (percentage)’.