Beta-2 microglobulin as a predictor of peripheral arterial disease in diabetes: The effect of estimated glomerular filtration

Background: Peripheral arterial disease (PAD) is common in patients with type 2 diabetes mellitus. Its definitive diagnosis requires ultrasound or angiography. Beta-2 microglobulin (a2 microglobulin) has been proposed as a diagnostic marker for PAD. The objective of the study was to evaluate the diagnostic value of a2 microglobulin for PAD in patients with diabetes and varying renal function. Design: This was a cross-sectional study. Setting: An academic centre (University of Pretoria and Steve Biko Academic Hospital Diabetes Clinic). Subjects: One hundred and eight convenience-sampled patients. Outcome measures: Patients completed a questionnaire and had toe and arm blood pressure (toe-arm index), as well as serum a2 microglobulin and creatinine, measured. Results: Beta-2 microglobulin did not differ (p-value = 0.34) between those subjects with PAD (n = 43) and those without PAD (n = 65). In a linear regression model, the interaction term between estimated glomerular filtration rate categories and the inverse of a2 microglobulin was highly significant (p-value = 0.001). Conclusion: Although the sample size was small, a2 microglobulin did not distinguish between subjects with and without PAD. Renal function and its effects on the association between a2 microglobulin and PAD need further study.