Diabetes is a disease that damages various organs due to increased levels of blood sugar. One of such organs is the skin. However, the actual importance of the skin in diabetes arises in the diagnosis. Early skin signs impel us to insistently search for the disease. These signs and symptoms are sclerodactyly, necrobiosis lipoidica, leg wounds, common fungal and bacterial infections, annular migratory erythema (necrolytic migratory erythema) in glucagonoma, and hair loss (telogen effluvium).

Like other tissues such as eyes, kidneys, nerves and vessels, the skin is also affected from the increased levels of blood sugar. Any complications appearing on the organs are compared to the results of Hemoglobin A1C (HBA1C), the indicative of blood sugar levels of the last two months, to determine if any parallelism therebetween is present.

Hemoglobin is degraded and removed from the body within two months which corresponds to the lifetime of red blood cells called erythrocytes. The high blood sugar leads to glycosylation in hemoglobin, and the glycosylated hemoglobin (HBA1C) remains in blood for 2 months until the removal of hemoglobin from the body. Hemoglobin reaches to all organs through blood, and glycosylate organ proteins too. In the skin, the collagen molecule is glycosylated. Collagen is a continuously degraded and rebuilt protein in young population, and becomes a degradation-resistant molecule in elderly and diabetic patients due to glycosylation and old collagen thus accumulates and no new collagen is produced. This phenomenon is an indicative of skin aging in elderly individuals and diabetics.