Effects of hydroquinone-containing creams on capillary glycemia before and after serial hand washings in Africans

Abstract

Background Hydroquinone-containing creams cause false increases in capillary glycemia. However, the magnitude of this false increase, and the means to reverse it have not been investigated. Objective To evaluate the technical and clinical impact of hydroquinone-containing creams on capillary glycemia and investigate the efficacy of hand washing and other common practices, in reversing cream effects. Methods We included 91 participants in a quasi-experimental study in Buea, Cameroon. After determining the hydroquinone content of a cream, Caro Light, we used two glucometers with different enzymatic systems (Accu-Chek Active and OneTouch Ultra 2) to measure fasting glycemia after: initial hand washing (reference), application of 1 ml of hydroquinone-containing cream, finger swabbing with wet gauze, sanitizer application and a series of three hand washings following cream application. Reference glycemia was compared to those obtained after various interventions. Statistical significance was assessed by paired sample t-test, clinical significance by total error allowable (TEa), and clinical impact by Parke’s error grid analysis. Results The mean differences in capillary glycemia (Intervention—reference) measured by Accu-Chek Active in mg/dl were 28, 27, 38, 16, 4, and -2 after cream application, finger swabbing, sanitizer application, one, two, and three hand washings respectively. Corresponding values for OneTouch Ultra2 were 41, 44, 64, 22, 5 and -5. These differences, except after two and three hand washings were both statistically (p < 0.0001) and clinically significant (TEa). After cream application, Accu-Check had 9.9% of values in Parke’s Zones C-E, while OneTouch had 18.7%. Conclusion Hydroquinone-containing creams cause significant false increase in capillary glycemia irrespective of the enzymatic system of the glucometer used, and can lead to potentially wrong clinical decisions. A minimum of two hand washings is required prior to capillary glucose measurement.