TABLE 2.
Incidence Proportion and Crude Incidence Density (Incident Cases per 1000 Person-Years at Risk) of Type 2 Diabetes Mellitus Associated With Baseline Characteristics, by Racial Group: Alameda County Study, 1965–1999
| Blacks (n = 648) |
Whites (n = 4774) |
|||||
| Variable Category | Total No. of Incident Cases | % With Diabetes | Incidence Density | Total No. of Incident Cases | % With Diabetes | Incidence Density |
| Total population | 51 | 7.9 | 4.2 | 211 | 4.4 | 2.0 |
| Age, y | ||||||
| < 40 | 24 | 8.7 | 4.8 | 105 | 4.9 | 2.0 |
| ≥ 40 | 27 | 7.2 | 3.8 | 106 | 4.0 | 2.0 |
| Gender | ||||||
| Women | 29 | 8.3 | 4.4 | 108 | 4.2 | 1.9 |
| Men | 22 | 7.3 | 4.0 | 103 | 4.6 | 2.1 |
| Marital status | ||||||
| Married | 34 | 7.8 | 4.1 | 166 | 4.6 | 1.9 |
| Unmarried | 17 | 7.9 | 4.3 | 45 | 4.0 | 2.0 |
| Height | ||||||
| Below mean | 25 | 7.3 | 3.8 | 105 | 4.4 | 2.0 |
| Above mean | 26 | 8.5 | 4.6 | 106 | 4.5 | 1.9 |
| Childhood SEPa | ||||||
| Low | 39 | 8.4 | 4.4 | 133 | 5.7b | 2.6 |
| High | 12 | 6.6 | 3.5 | 78 | 3.2 | 1.5 |
| Education, y | ||||||
| ≤ 12c | 34 | 6.7b | 3.6 | 143 | 4.9b | 2.4 |
| > 12 | 17 | 12.3 | 6.6 | 68 | 3.7 | 1.5 |
| Income tertile | ||||||
| Low | 18 | 8.3 | 4.5 | 82 | 5.2 | 2.4 |
| Moderate | 15 | 7.0 | 3.5 | 64 | 4.0 | 1.8 |
| High | 18 | 8.3 | 4.7 | 65 | 4.1 | 1.7 |
| Occupation | ||||||
| Blue collar | 28 | 8.0 | 4.2 | 56 | 4.9 | 2.4 |
| White collar | 14 | 10.8 | 5.9 | 93 | 4.6 | 2.0 |
| Health insurance | ||||||
| No | 16 | 8.5 | 5.0 | 14 | 2.5b | 1.3 |
| Yes | 35 | 7.6 | 3.9 | 197 | 4.7 | 2.0 |
| Regular health provider | ||||||
| No | 16 | 9.5 | 5.7 | 35 | 3.5 | 1.6 |
| Yes | 35 | 7.3 | 3.7 | 176 | 4.7 | 2.1 |
| Depression | ||||||
| Yes | 9 | 8.2 | 4.6 | 29 | 4.5 | 2.3 |
| No | 42 | 7.8 | 4.1 | 182 | 4.4 | 1.9 |
| High blood pressure | ||||||
| Yes | 10 | 9.4 | 5.4 | 26 | 6.1 | 3.7 |
| No | 41 | 7.6 | 4.0 | 185 | 4.3 | 1.8 |
| BMI categoryd | ||||||
| Obesec | 10 | 13.3e | 6.9 | 36 | 16.6e | 8.3 |
| Overweight | 20 | 8.3 | 4.3 | 68 | 5.5 | 2.5 |
| Normal/underweight | 21 | 6.3 | 3.4 | 107 | 3.2 | 1.4 |
| Waist circumference | ||||||
| Largef | 7 | 13.0 | 7.4 | 29 | 11.3b | 6.9 |
| Normal | 44 | 7.4 | 3.9 | 182 | 4.0 | 1.8 |
| Physical activity level | ||||||
| Inactive/low | 22 | 8.4 | 4.8 | 57 | 4.1 | 2.1 |
| Moderate | 22 | 8.3 | 4.3 | 102 | 4.7 | 2.0 |
| High | 7 | 5.8 | 2.9 | 52 | 4.3 | 1.7 |
| Smoking status | ||||||
| Current smoker | 30 | 9.1 | 5.0 | 106 | 5.0e | 2.2 |
| Former smoker | 6 | 6.8 | 4.2 | 45 | 5.7 | 2.4 |
| Never smoked | 15 | 6.5 | 3.2 | 60 | 3.3 | 1.4 |
| Drinking | ||||||
| Abstention | 16 | 7.7 | 4.3 | 31 | 3.8 | 1.9 |
| 1–45 drinks/mo | 28 | 7.7 | 4.0 | 147 | 4.6 | 2.0 |
| ≥ 46 drinks/mo | 7 | 9.0 | 4.6 | 33 | 4.3 | 1.9 |
Note. BMI = body mass index; SEP = socioeconomic position.
Childhood SEP was based on a respondent's father's occupation (or education when occupation data were not available [6.5% of total]), as follows: low = manual (blue-collar) occupation or 12 years or fewer of education; high = white-collar occupation or more than 12 years of education [reference]).
P < .05, by the χ2 test for proportional difference in distribution of covariate category by racial group.
P < .05, for interaction between covariate category and racial group.
BMI categories were as follows: obese = 30 kg/m2 or more; overweight = 25.0–29.9 kg/m2; normal and underweight = 24.9 kg/m2 or lower.
P < .05, by the χ2 test for trend across covariate categories within racial group.
Large waist circumference was defined as more than 34.6 inches for women and more than 40.2 inches for men.