Table 1

Baseline individual-level characteristics of three independent study samples in the Diabetes LEAD Network

StudyVADRREGARDSGeisinger
Geographic coverage3108 counties across USA (71 835 census tracts)1349 counties across USA (7502 census tracts)37 counties in Pennsylvania
(785 census tracts)
Study designRetrospective EHR-based cohortProspective population-based cohortRetrospective EHR-based nested case–control
Study period2008–20182003–20162008–2016
CasesControl encounters
Follow-up or contact time, years, median (IQR)*5.0 (2.4,9.0)9.5 (8.7, 9.9)11.2 (7.5, 14.1)11.2 (7.5, 14.1)
Number of participants4 100 65011 20815 88879 435
Number of new onset diabetes cases539 3691409NANA
Age, years, mean (SD)59.4 (17.2)63.0 (8.5)54.9 (15.1)54.9 (15.3)
Age, n (%)
 10–17NANA230 (1.5)1184 (1.5)
 18–34486 304 (11.9)NA1361 (8.6)6771 (8.5)
 35–49637 553 (15.6)649 (5.8)4038 (25.4)20 189 (25.4)
 50–641 332 938 (32.5)5884 (52.5)6202 (39.0)31 007 (39.0)
 65–791 087 570 (26.5)4321 (38.6)3331 (21.0)16 654 (21.0)
 80+556 227 (13.6)354 (3.2)726 (4.6)3630 (4.6)
Sex, female, n (%)321 013 (7.8)6256 (55.8)7798 (49.1)38 988 (49.1)
Race/ethnicity, n (%) †
 Non-Hispanic White2 783 756 (76.3)7534 (67.2)15 112 (95.1)76 971 (96.9)
 Non-Hispanic Black584 655 (16)3674 (32.8)293 (1.8)905 (1.1)
 Hispanic189 177 (5.2)NA369 (2.3)1094 (1.4)
 Asian34 838 (1.0)NA63 (0.4)267 (0.3)
 Other/unknown56 804 (1.6)NA51 (0.32)198 (0.3)
Smoking status, n (%)†
 Current smoker610 506 (40.3)1245 (11.1)3272 (20.6)14 831 (18.7)
 Non-smoker (former or never)902 901 (59.7)9926 (88.9)12 223 (76.9)63 241 (79.7)
HbA1c, mean (SD) ‡ †5.7 (0.6)NA7.3 (1.9)5.6 (0.4)
  • *Follow-up time (VADR and REGARDS) or contact time (Geisinger): VADR: cohort subjects were followed from the date of cohort entry until censoring defined as date of incident T2D, death, no encounters with the VA system for 2 years, or the end of the study. REGARDS: follow-up time was measured as the time between the two in-home visits. Geisinger: time from first clinical encounter to T2D onset or clinical encounter during matched encounter year.

  • †Missing data: VADR: race/ethnicity, 451 420 (11% missing); smoking status, 2 587 243 (63% missing); HbA1C, 2 423 788 (59% missing); REGARDS: smoking status, 37 (0.3% missing); Geisinger: HbA1C: 8391 (53% missing) cases and 75 280 (95% missing) controls.

  • ‡All baseline clinical measures: VADR: most recent measure prior or on cohort entry date. REGARDS: at enrollment. Geisinger: closest within 1 year prior to T2D diagnosis/matched encounter date.

  • HbA1c, hemoglobin A1c; IQR, Interquartile range (25th, 75th percentile); NA, not applicable; REGARDS, REasons for Geographic and Racial Differences in Stroke; T2D, type 2 diabetes; VADR, Veterans Administration Diabetes Risk.