Diabetic mastopathy is an uncommon fibrous breast condition that sometimes occurs in patients who have had diabetes for a long time. Hard, benign (non-cancerous) lumps may appear in one breast or both breasts.

Diabetic mastopathy usually affects women with type 1 diabetes. The disorder is also more common in women who have microvascular (small blood vessel) complications such as diabetic retinopathy or diabetic nephropathy. In addition, diabetic mastopathy may affect women with type 2 diabetes or other forms of diabetes and, in rare cases, diabetic men.

Because the lumps associated with diabetic mastopathy are benign, the disorder is not life-threatening. However, the lumps can be similar in size, shape and texture to malignant (cancerous) lumps and are sometimes misdiagnosed as potentially cancerous breast tissue.

Several diagnostic techniques, including a biopsy, may be required to confirm the diagnosis. Surgery may be recommended to remove a portion of the lump or the entire lump, although reoccurrence after removal is common.

An annual breast exam performed by a physician can help detect diabetic mastopathy and other disorders, including cancer. The examination may include a mammogram (x-ray image of the breast) and ultrasound imaging. 

Because little is known about the causes of diabetic mastopathy, there are no established prevention methods.