Structural analysis of a micron-sized deposit of Cu⁰ in an insulin ball from a person with diabetes⁰ in a person with diabetes's insulin ball

People with diabetes take insulin preparations to maintain optimal blood sugar (glucose) levels in the body. Insulin preparations can form insoluble structures in the body called "insulin balls" when repeatedly injected into the same site. We found maximum100 µm-sized deposits of copper within an insulin ball in a woman in her mid-40s with diabetes. Copper is known to accumulate in such living things as plants and bacteria, we found the largest copper mass in living organisms. Copper is essential for living organisms, but too much can be poisonous. Copper ion concentrations have been thought to be strictly regulated in vivo. The significance of copper deposits within insulin balls should be further investigated to see if there are negative consequences of their presence in people with diabetes.