Table 2.
Average difference in 20-year decline in global cognitive Z score, delayed word recall, digit symbol substitution, and word fluency among persons with a history of diagnosed diabetes compared to persons without diabetes
| No attrition adjustment | ||||
|---|---|---|---|---|
| Test | 20 year decline – No diabetes Estimate (95% CI) |
20 year decline – Diabetes Estimate (95% CI) |
Difference* Estimate (95% CI) |
Percent† |
| Global Z | -0.78 (-0.80, -0.75) | -0.92 (-1.00, -0.85) | -0.15 (-0.22, -0.08) | 19% |
| Delayed Word Recall Test | -0.98 (-1.02, -0.94) | -1.04 (-1.15, -0.92) | -0.06 (-0.17, 0.06) | 6% |
| Digit Symbol Substitution Test | -0.69 (-0.71, -0.67) | -0.82 (-0.87, -0.77) | -0.13 (-0.18, -0.08) | 19% |
| Word Fluency Test | -0.17 (-0.19, -0.14) | -0.28 (-0.35, -0.22) | -0.12 (-0.18, -0.06) | 71% |
| Attrition-adjusted | ||||
| Test | 20 year decline – No diabetes | 20 year decline – Diabetes | Difference* | Percent† |
| Global Z | -0.79 (-0.82, -0.76) | -1.01 (-1.11, -0.92) | -0.23 (-0.32, -0.13) | 29% |
| Delayed Word Recall Test | -1.01 (-1.05, -0.96) | -1.09 (-1.22, -0.96) | -0.09 (-0.22, 0.04) | 9% |
| Digit Symbol Substitution Test | -0.70 (-0.72, -0.68) | -0.87 (-0.94, -0.81) | -0.18 (-0.24, -0.11) | 26% |
| Word Fluency Test | -0.17 (-0.20, -0.14) | -0.37 (-0.47, -0.28) | -0.21 (-0.31, -0.10) | 124% |
Calculated as the difference in 20-year decline between persons without and with diabetes (negative values indicate greater decline in persons with diabetes)
Calculated as the difference expressed as a percentage of the decline in those without diabetes. That is, (decline in participants without diabetes – decline in participants with diabetes)/(decline in participants without diabetes); thus a value of 19% indicates a 19% greater decline in those with diagnosed diabetes compared to those without. Note that the differences and percent declines are calculated before rounding of 20-year estimates.
Note: bold values indicate p-value < 0.05. Z scores can be interpreted as standard deviations above or below the mean. For example, a Z score difference of -0.15 means that, on average, persons with diabetes declined an additional 0.15 standard deviations compared to persons without diabetes. Time since baseline was the time metric, and cognitive function was modeled using generalized linear models fit using generalized estimating equations, with adjustment for age, age squared, race-center, sex, education, cigarette smoking, alcohol consumption, body mass index, hypertension, history of coronary heart disease, history of stroke, APOE ε4 genotype, and interactions between all of these covariates and time. N=30,058 total records, with N=13,351 participants at visit 2(N=1,779 with diabetes), N=10,720 at visit 4(N=1,209 with diabetes), and N=5,987 at visit 5(N=446 with diabetes).