Sagittal abdominal diameter (sad) in comparison with other anthropometric methods and its correlation with insulin resistance in pre-diabetes

Background: The likelihood of future progression to diabetes mellitus can be assessed using various indicators of insulin resistance. Waist circumference, body mass index (BMI) and waist hip ratio are routinely employed in estimating obesity, which in turn contributes to insulin resistance. Sagittal abdominal diameter (SAD), is measured with the patient in supine position, causing the subcutaneous fat to fall down towards either side, and hence leaving the harder visceral fat to be measured by SAD. Waist circumference, however, measures both subcutaneous and visceral fat. SAD has been shown to have strong correlations with impaired glucose tolerance, insulin resistance and risk of cardiovascular disease. The purpose of this study was to evaluate the utility of SAD in relation to insulin resistance in people with pre-diabetes and to compare it with waist circumference and BMI. Method: People with pre-diabetes were included in the study. The sample size was calculated based on previous studies using Pearson’s correlation coefficient (r=0.62) to be 86. We determined SAD, waist circumference, BMI and insulin resistance (using HOMA-IR formula) in them and tried to find the correlation between the anthropometric measurements and insulin resistance. Result: SAD and BMI were found to have a very highly significant correlation with insulin resistance (r=0.447, p <0.001 and r=0.495, p <0.001 respectively) whereas waist circumference had significant correlation (r=0.286, p=0.008). Conclusion: SAD appeared to be a better correlate of insulin resistance than waist circumference in pre-diabetes. Hence it is a potentially simple, cheap and non invasive tool to assess insulin resistance in pre-diabetics.