Does the 'slipping slipper sign' in patients with diabetes predict the presence of retinopathy and nephropathy?

Abstract

Previous research had noted that an affirmative response in patients with diabetes to the question 'Have you ever lost your slipper/flip-flop from your feet while walking and not realised that you have done so'? That is, the presence of the 'slipping slipper sign' (SSS) reflected the presence of severe diabetic peripheral neuropathy with a high degree of precision. The objective of the current study was to determine whether the SSS may also predict the presence of diabetic retinopathy and/or nephropathy since microvascular complications are known to cosegregate. Among 100 patients with diabetes, including 33 cases with the SSS and 67 controls without the SSS, data on demography, dipstick proteinuria as well as the presence and staging of diabetic retinopathy were obtained. The mean (SD) age of all patients was 54.6 (13.0) years, mean duration of diabetes was 12.7 (10.2) years and mean haemoglobin A1c (HbA1c) 8.42 (1.95) %; 43% were males. All 33 (100%) of the patients with SSS but only 12 (18%) of the patients without SSS were found to exhibit diabetic retinopathy, p<0.001. Among those patients with retinopathy, proliferative retinopathy was far more likely (39%) in the SSS group compared with non-SSS subjects (8%). Similarly, 15 (46%) with SSS and only 4 (6%) without SSS were found to have dipstick proteinuria. The sensitivity of the SSS for retinopathy was 73% and the specificity was 100% with a positive predictive value (PPV) of 100% and negative predictive value (NPV) of 82%. For proteinuria, both the sensitivity and specificity was 78%. Both diabetic retinopathy and dipstick proteinuria are strongly associated with the presence of the SSS that therefore holds potential as a tool for easier identification of this high-risk group.