The thickness of the stratum corneum was measured by optical coherence tomography at the center and sides of the tactile elevations of all fingers in 87 healthy volunteers and 18 people with diabetes who performed regular glucose self-control. The cornified epidermis was thickest at the thumbs, and thickness decreased toward the little finger. The cornified epidermis was thinner at the sides of the tactile elevations than at the center, and it was thinner in women than in men. In people with diabetes, the cornified epidermis of the fingers most frequently used for capillary blood sampling was not conspicuously thickened.