Effects of hydroquinone-containing creams on capillary glucose measurements before and after serial hand washings

Abstract

Introduction : hydroquinone-containing skin lightening creams cause false increase in capillary glycaemia. As a means of preventing false results, patients usually have their fingers swabbed with water soaked gauze or apply hand sanitizers before measurement. The objective was to determine the effect of hydroquinone-containing creams on capillary glucose measurement in terms of technical and clinical impact and the number of hand washings needed to prevent these effects. Methods : we included 91 consenting diabetic and non-diabetic participants in a quasi-experimental study in Buea. Two glucometers with different enzymatic principles (Accu-Check®active andOneTouch®ultra2), were used to measure fasting glycaemia after hand washing (reference), calibrated cream application, finger swabbing, sanitizer application and a series of 3 hand washing following cream application. Results : the mean difference in capillary glycaemia between the reference value and the values after the various interventions measured using Accu-Check®active were -28, -27, -38, -16, -4 and 2 respectively after cream application, finger swabbing, sanitizer application and three series of hand washings. Corresponding values measured using OneTouch®Ultra2 in mg/dl were -41, -44, -64, -22, -5 and 5. The mean cream-attributed glucose increment was 28mg/dl for Accu-Check®active and 41 mg/dl for OneTouch®ultra2.After cream application, Accu-Check®active had 9.9% of values in Parke’s Zones C-E, while OneTouch®ultra2had 18.7%. Conclusion : hydroquinone containing creams cause a significant false increase in capillary glycaemia irrespective of the enzymatic principle of the glucometer used, leading to 10 to 19% potentially wrong clinical decisions. Finger swabbing with wet gauze or application of hand sanitizers are insufficient in reversing the effect of these creams. A minimum of two hand washing is required prior to capillary glucose measurement.