Cross-Sectional Evaluation of Noninvasively Detected Skin Intrinsic Fluorescence and Mean Hemoglobin A1c in Type 1 Diabetes

Background: This study evaluated the relationship between skin intrinsic fluorescence (SIF) and long-term mean hemoglobin A1c (HbA1c) in individuals with type 1 diabetes. Subjects and Methods: We undertook a cross-sectional analysis of 172 individuals with type 1 diabetes followed longitudinally with HbA1c data available over an average of 16.6 years. SIF was evaluated cross-sectionally using the SCOUT DS (R) device (VeraLight Inc., Albuquerque, NM) and correlated with most recent HbA1c and long-term mean HbA1c. Potential determinants of this relationship, including age, gender, smoking status, duration of diabetes, and renal function, were also evaluated. Results: Age-adjusted skin intrinsic fluorescence significantly correlated with long-term mean HbA1c (R = 0.44, P < 0.0001). In contrast, there was no significant relationship between SIF and most recent HbA1c (R = 0.14, P = 0.075). The best-fit model describing the relationship between SIF and mean HbA1c controlled for factors of age, duration of disease, renal function, and site of study conduct. Controlling for these factors was also important in understanding the relationship between most recent HbA1c and SIF. Evaluating longer-term HbA1c data also strengthened the relationship between SIF and mean HbA1c. In the presence of renal dysfunction or damage, as indicated by an estimated glomerular filtration rate of < 60 mL/min/1.73m(2) or presence of gross proteinuria, there was no significant correlation between SIF and mean HbA1c. Conclusions: Noninvasive detection of SIF significantly correlates with long-term mean HbA1c, providing insight into long-term glycemic exposure. Age, duration of diabetes, and renal function are potential contributors to this relationship.