Xanthochromia of the skull bone associated with HbA1c

• Positive correlation between yellowing of the skull bone and HbA1c.
• Positive correlation between age and HbA1c.
• Inverse correlation between age and brightness of the bone.
• No significant correlation between diabetes mellitus and brightness of the bone.

The color of the surface of 105 skull bones (part of the parietal bone) was determined using a portable spectral colorimeter (spectro color®). By this means it was possible to characterize the color objectively according to the L*a*b* color system defined by the “International Commission de l’Eclairage” (CIE). Biochemical markers of carbohydrate metabolism, HbA1c from venous blood, and glucose/lactate concentrations from vitreous humor, were also determined, for assessment of the ante-mortem plasma glucose concentration using Traub's sum formula. As biochemical markers for lipid metabolism disorder, cholesterol, triglycerides, high density lipoprotein (HDL), low density lipoprotein (LDL) and very low density lipoprotein (VLDL) were all determined from venous blood. There is a significant correlation of bone yellowing with HbA1c (p < 0.001) and age (p < 0.001). The literature asserts a significant correlation between diabetic condition and yellowing of the skull bone. Despite efforts to find the substance responsible for the yellowing of the bone in chronic metabolism disorder, no significant correlation was found between bone color and lipoproteins/bone extracted lipid acids.