Table 4. Incidence rates and hazard ratios for impaired insulin secretion and insulin resistance according to pack‐years of cigarette smoking.
| Never‐smokers | Current smokers | P for trendb | |||
|---|---|---|---|---|---|
| 0 Pack‐years | 0.1–20.0 Pack‐years | 20.1–30.0 Pack‐years | ≥30.1 Pack‐years | ||
| n | 353 | 68 | 70 | 125 | |
| Impaired insulin secretion | |||||
| Cases (n)/person‐years | 122/1,009 | 24/181 | 30/182 | 60/328 | |
| Incidence rate (per 1,000 person‐years) | 120.9 | 132.6 | 164.8 | 182.9 | |
| Age‐adjusted HR (95% CI) | 1.0 | 1.17 (0.75–1.82) | 1.42 (0.95–2.13) | 1.46 (1.07–1.99) | 0.003 |
| Multivariable‐adjusted HR (95% CI)a | 1.0 | 1.74 (1.09–2.76) | 1.92 (1.25–2.96) | 2.09 (1.46–2.99) | <0.001 |
| Insulin resistance | |||||
| Cases (n)/person‐years | 22/1216 | 6/215 | 9/237 | 18/413 | |
| Incidence rate (per 1,000 person‐years) | 18.1 | 27.9 | 38.0 | 43.6 | |
| Age‐adjusted HR (95% CI) | 1.0 | 1.60 (0.64–3.97) | 2.16 (0.99–4.73) | 2.40 (1.29–4.47) | <0.001 |
| Multivariable‐adjusted HR (95% CI)a | 1.0 | 0.97 (0.40–1.79) | 1.07 (0.55–2.55) | 1.18 (0.65–2.19) | 0.39 |
a
Adjusted for age, familial history of diabetes (yes or no), alcohol consumption (0, 1–139 or ≥140 g/week), exercise (0, 1–119 or ≥120 min/week), systolic blood pressure, log‐transformed triglyceride, log‐transformed γ‐glutamyltransferase, waist circumference, leukocyte count, changes in smoking status between the baseline and final examinations (no change or quitted smoking) and Δ waist circumference (Δ = final examination minus baseline examination).
b
Calculated across increasing categories of pack‐years of cigarette smoking. Pack‐years: one pack has 20 cigarettes.
CI, confidence interval; HR, hazard ratio.