Skin Carotenoid Score as an Important Prognostic Factor for Predicting Type 2 Diabetes Mellitus in Middle-Aged Subjects

This study aimed at identifying middle-aged subjects at risk for developing type 2 diabetes mellitus using noninvasive skin carotenoid and vascular function measurements. To this end, 61 subjects (40–65 years of age) without type 2 diabetes mellitus (Group A, Hemoglobin A1c < 6.5%) and 69 subjects (40–65 years of age) with type 2 diabetes mellitus (Group B, Hemoglobin A1c ≥ 6.5%) were recruited (Table 1). The skin carotenoid score was recorded using spectroscopy-based skin carotenoid measurements that approximate dietary fruit and vegetable intake. Endothelial function and heart rate variability were measured for the two groups and correlated with skin carotenoids scores. The daily vegetable and fruit intake was positively correlated with the skin carotenoids score in both groups (Group A, r = 0.598, p < 0.001; Group B, r = 0.449, p < 0.001). There were also significant differences in skin carotenoids score, indices of endothelial function, and heart rate variability between the subjects in group A and group B. There was a negative correlation between skin carotenoids score and individual determinants of metabolic syndrome, including high-density lipoprotein (r = −0.361, p = 0.009), waist circumference (r = −0.450, p < 0.001), fasting blood sugar (r = −0.713, p < 0.001), and Hemoglobin A1c (r = −0.808, p < 0.001); however, systolic blood pressure showed no significant correlation (p = 0.06). In conclusion, carotenoids and cardiovascular parameters are reliable predictive factors of type 2 diabetes mellitus in middle-aged subjects.