Skin autofluorescence and complications of diabetes: does ethnic background or skin color matter?

Aims: Skin autofluorescence (AF) has been associated with complications of diabetes. We evaluated the influence of skin color and ethnicity on the association between skin AF and the presence of diabetes-related complications. Materials and Methods: In a multiethnic type 2 diabetes cohort we investigated all patients with available skin AF measurements. The associations between skin AF and hemoglobin A1c (HbA1c) and the presence of complications of diabetes were estimated, stratified for ethnicity and quartiles of ultraviolet reflectance percentage (R%). Results: In total, 810 patients (438 native Dutch, 372 non-Dutch) were included. Because of too low an R%, 32% of black Africans and 19% of Hindustanis were excluded. Non-Dutch patients had lower AF values compared with Dutch patients (median AF=2.69 [interquartile range (IQR), 2.26-3.09] vs. 3.06 [IQR, 2.65-3.50] arbitrary units; P<0.001), but the R% was also lower (non-Dutch, median R%=12% [IQR, 9-15%]; Dutch, median R%=18% [IQR, 14-23%]; P=0.027). In the multivariate analysis, skin AF was only a determinant for complications in patients with R% 25(th) percentile (macrovascular, odds ratio [OR]=1.71 [95% confidence interval (CI), 1.05-2.77] vs. 1.15 [95% CI, 0.55-2.40] in the lowest quartile of R%; microvascular, OR=1.81 [95% CI, 1.20-2.75] vs. OR=0.87 [95% CI, 0.50-1.51]). A similar pattern was observed for nephropathy, neuropathy, and retinopathy separately. In non-Dutch patients AF was not a significant determinant for diabetes complication risk, whereas HbA1c was for nephropathy, retinopathy, and neuropathy. Conclusions: Skin AF measurement is a valuable tool for the assessment of micro- and macrovascular complication risk in patients with light skin color types. Even after exclusion of patients with too low a reflectance, the current performance of the AGE Reader (TM) (DiagnOptics Technologies BV, Groningen, The Netherlands) was insufficient in darker-skinned patients.