Out of the 658 subjects entered into this analysis, 145 had type 2 diabetes. Because 194 subjects had IGT, the remaining 319 subjects were classified as the comparison population, making the total analysis sample size 464. Baseline characteristics by diabetes status and sex are shown in . Compared to those without diabetes, men and women with type 2 diabetes differed significantly by mean age, weight, height, BMI, IAF area, upper arm length, and (in men only) total arm length and total and lower leg length.
Baseline characteristics of study subjects subdivided by sex and diabetes status
Analyses examining whether potential confounders were associated with both dependent (diabetes) and independent (arm length, leg length and height) variables were performed. Age, weight, IAF area, family history of diabetes and smoking status were significantly associated with both (p<0.05). In addition, sex and height were included in multivariable models because of their associations with limb length.
When controlling for explanatory and confounding variables (age, sex, IAF area, height, weight, smoking status and family history of diabetes) using multivariable logistic regression models, a number of associations between arm length measurements and diabetes became apparent (). Total arm length (OR 0.49; 95% CI 0.29, 0.84) and upper arm length (OR 0.56; 95% CI 0.36, 0.87) were inversely related to diabetes, while forearm length was positively associated with diabetes (OR 1.24; 95% CI 0,93, 1.65). Total leg length, lower leg length and height did not show a statistically significant association with diabetes after adjustment for potential confounders (age, sex, IAF area, weight, smoking status and family history of diabetes) (). There were no statistically significant interactions between the different limb length measurements and any of the covariates shown in the fully-adjusted models in and (sex * total arm length, p=0.126; sex * upper arm length, p=0.492; sex * forearm length, p=0.358; sex * total leg length, p=0.223; sex * lower leg length, p=0.157 and sex * height, p=0.598). The quadratic transformations of the limb length measurements were not significant in the multivariable models, therefore a linear relation can be assumed.
Odds ratios (95%-CI) of prevalent diabetes for a 1-SD increase in total arm length, upper arm length and forearm length, adjusted for possible explanatory and confounding factors
Odds ratios (95%-CI) of prevalent diabetes for a 1-SD increase in total leg length, lower leg length and height, adjusted for possible explanatory and confounding factors
Even though there was no significant interaction between sex and arm length measurements, sex-specific analyses for the associations between arm lengths and diabetes were performed. The sex specific findings in adjusted models are shown in . The associations between upper and total arm length and diabetes odds are of greater magnitude in men compared to women.
Figure 1 Odds ratio of diabetes by arm measurements in men (A) and women (B). Odds ratio with 95% confidence intervals for diabetes are illustrated per 1-s.d. increase in arm measurements, corrected for age, IAF area, height, weight, smoking status and family (more ...)
A sensitivity analysis was performed that excluded subjects who had diabetes at baseline or who developed diabetes in the 10-year follow-up period. This analysis yielded similar results to those shown in and . The analyses in and were re-run after including subjects with IGT in the comparison group, and these results were nearly identical to those described above.