Table 2. HR (95% CI) for incident type 2 diabetes by the season of birth among 461,211 participants.
| Spring | Summer | Autumn | Winter | Combined category of Spring, Autumn, and Wintera | |
|---|---|---|---|---|---|
| Whole cohort | |||||
| No. of person-years | 753,382 | 800,360 | 918,565 | 819,588 | 2,491,535 |
| No. of cases | 1,971 | 1,996 | 2,523 | 2,294 | 6,788 |
| Age adjusted | 1.09 (1.02, 1.16) | 1.00 | 1.07 (1.01, 1.14) | 1.07 (1.01, 1.14) | 1.08 (1.02, 1.13) |
| Multivariable adjustedb | 1.09 (1.02, 1.16) | 1.00 | 1.07 (1.01, 1.14) | 1.07 (1.01, 1.14) | 1.08 (1.02, 1.13) |
| +BMI at baseline | 1.09 (1.02, 1.16) | 1.00 | 1.08 (1.02, 1.15) | 1.09 (1.02, 1.15) | 1.09 (1.03, 1.14) |
| Men | |||||
| No. of person-years | 301,255 | 323,106 | 375,124 | 337,313 | 1,013,691 |
| No. of cases | 727 | 721 | 966 | 845 | 2,538 |
| Age adjusted | 1.11 (1.00, 1.23) | 1.00 | 1.12 (1.02, 1.24) | 1.07 (0.97, 1.18) | 1.10 (1.01, 1.19) |
| Multivariable adjustedb | 1.10 (0.99, 1.22) | 1.00 | 1.12 (1.02, 1.23) | 1.06 (0.96, 1.18) | 1.10 (1.01, 1.19) |
| +BMI at baseline | 1.10 (0.99, 1.22) | 1.00 | 1.13 (1.03, 1.25) | 1.08 (0.98, 1.20) | 1.11 (1.02, 1.20) |
| Women | |||||
| No. of person-years | 452,127 | 477,255 | 543,441 | 482,275 | 1,477,844 |
| No. of cases | 1,244 | 1,275 | 1,557 | 1,449 | 4,250 |
| Age adjusted | 1.08 (1.00, 1.17) | 1.00 | 1.05 (0.97, 1.13) | 1.07 (0.99, 1.16) | 1.07 (1.00, 1.13) |
| Multivariable adjustedb | 1.08 (1.00, 1.17) | 1.00 | 1.05 (0.98, 1.13) | 1.07 (1.00, 1.16) | 1.07 (1.00, 1.14) |
| +BMI at baseline | 1.08 (1.00, 1.17) | 1.00 | 1.06 (0.98, 1.14) | 1.09 (1.01, 1.17) | 1.07 (1.01, 1.14) |
Reference group: Summer-born participants.
Multivariable model was adjusted for: age (years); sex (male or female, for whole cohort); level of education (no formal school, primary school, middle school, high school, college, or university or higher); marital status (married, widowed, divorced or separated, or never married); alcohol consumption (not weekly drinker, weekly but not daily drinker, daily drinker with <15, 15 to 29, 30 to 59, or ≥25 grams per day); smoking status (never or occasional smoker, former smoker having quit smoking ≥5, or <5 years, or current daily smoker with <15, 15 to 24, 30 to 59, or ≥25 cigarettes per day); physical activity (MET-hr/day); intake frequencies of red meat, fresh fruits, and vegetables (daily, 4 to 6 days/week, 1 to 3 days/week, monthly, or rarely or never); family history of diabetes (presence, absence, or unknown); and menopausal status (premenopausal, perimenopausal, or postmenopausal; for women only).