Overall and ethnicity-stratified analysis reported in HRs (95% CI), complete case analysis (n=2189)
| Sleep variable | Number of type-2 diabetes occurrences and person-years followed up (Cases/P-Y) | Model 1 | Model 2 | Model 3 | P-value for interaction | |
| Difficulty Falling Asleep | No | Yes | ||||
| All | 383/30 741 | 101/6631 | 1.21 (0.96 to 1.54) | 1.18 (0.93 to 1.50) | 1.21 (0.95 to 1.54) | |
| Europeans | 136/17591 | 32/3324 | 1.26 (0.84 to 1.89) | 1.25 (0.83 to 1.89) | 1.26 (0.83 to 1.93) | – |
| South-Asians | 184/9708 | 48/2216 | 1.28 (0.91 to 1.79) | 1.12 (0.80 to 1.59) | 1.16 (0.82 to 1.65) | 0.748 |
| African-Caribbeans | 63/3442 | 21/1091 | 1.16 (0.65 to 2.10) | 1.18 (0.64 to 2.17) | 1.12 (0.62 to 1.99) | 0.786 |
| Early Morning Waking | No | Yes | ||||
| All | 272/22 367 | 212/15 005 | 1.12 (0.93 to 1.35) | 1.14 (0.94 to 1.38) | 1.11 (0.92 to 1.34) | |
| Europeans | 104/13 291 | 64/7624 | 1.04 (0.75 to 1.44) | 1.04 (0.75 to 1.44) | 1.00 (0.72 to 1.40) | – |
| South-Asians | 112/6294 | 120/5630 | 1.17 (0.90 to 1.53) | 1.21 (0.93 to 1.58) | 1.21 (0.92 to 1.58) | 0.392 |
| African-Caribbeans | 56/2782 | 28/1751 | 0.67 (0.38 to 1.19) | 0.68 (0.38 to 1.21) | 0.60 (0.33 to 1.09) | 0.133 |
| Waking up Tired | No | Yes | ||||
| All | 301/23 096 | 174/14 276 | 0.82 (0.68 to 1.01) | 0.80 (0.66 to 0.98) | 0.80 (0.66 to 0.98) | |
| Europeans | 104/12 757 | 64/8158 | 0.88 (0.62 to 1.21) | 0.84 (0.60 to 1.17) | 0.87 (0.62 to 1.22) | – |
| South-Asians | 155/7558 | 77/4366 | 0.75 (0.56 to 1.00) | 0.71 (0.53 to 0.95) | 0.72 (0.54 to 0.97) | 0.389 |
| African-Caribbeans | 51/2781 | 33/1752 | 1.16 (0.71 to 1.91) | 1.18 (0.72 to 1.94) | 1.14 (0.68 to 1.92) | 0.607 |
| Snoring | No | Yes | ||||
| All | 277/13 985 | 207/23 387 | 1.33 (1.10 to 1.60) | 1.32 (1.10 to 1.59) | 1.15 (0.96 to 1.39) | |
| Europeans | 100/7974 | 68/12 941 | 1.15 (0.83 to 1.58) | 1.12 (0.82 to 1.54) | 0.91 (0.67 to 1.23) | – |
| South-Asians | 123/4479 | 109/7445 | 1.53 (1.17 to 1.98) | 1.56 (1.20 to 2.03) | 1.41 (1.08 to 1.85) | 0.056 |
| African-Caribbeans | 54/1532 | 30/3001 | 1.07 (0.68 to 1.68) | 1.09 (0.69 to 1.72) | 0.93 (0.59 to 1.46) | 0.945 |
Model 1: adjusted for age, sex and ethnicity, socioeconomic position; model 2: model 1 plus physical activity and smoking status; model 3: model 2 plus BMI; P=p values for interaction by ethnicity (ethnicity*sleep quality exposure), alpha threshold=0.10, Europeans as the reference group. Bold values represent HR and 95%CI that do not cross 1.00 or P values for interaction by ethnicity <0.10.
BMI, body mass index; P-Y, person-years followed up.