Unexplained bruises

Originally Published: May 8, 1995 - Last Updated / Reviewed On: July 27, 2007
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Alice,

I seem to be having a lot of unexplained bruises, especially on my arms. My husband is worried that it could be a symptom of diabetes, which runs in my family. Does bruising have anything to do with diabetes?

— Black and blue

Dear Black and blue,


There are many reasons why bruises may unexpectedly appear; however, diabetes is an unlikely suspect. The connection between "bruising" and diabetes that your husband may be referring to is a condition called acanthosis nigricans, where patches of brown to black skin accumulate in the folds and creases of their bodies — usually in the armpits and neck. This hyper-pigmentation happens because insulin "spills over" into the skin due to insulin resistance associated with Type II Diabetes. Another connection is that sometimes bruises heal slower in people with diabetes; however this wouldn't explain why you are noticing more bruises in the first place. If you are worried about diabetes, there are more telling warning signs that you may want to pay attention to. For example, increased thirst and urination, extreme hunger, weight loss, fatigue, blurred vision, and frequent infections may result from a high blood-sugar level.

Unlike acanthosis nigricans, bruises are caused by leakage of blood after an injury. The list of usual suspects includes bumping into bedposts or other objects and not remembering, rigorous exercising (which can cause tiny tears in blood vessels, particularly in athletes and weightlifters), and old age.

Some people, especially women, are more prone to bruising than others, so one possible explanation may be that you are less likely to notice the injury that triggered the bruising. Moreover, as people grow older and continue to expose themselves to the damaging effects of the sun, the skin becomes more susceptible to bruising. With time, the skin thins, losing some of its fatty layer that cushions blood vessels against damage. Also, capillary walls become more fragile, and tissues that support blood vessels weaken as people age. So, the bumps — especially to the arms and legs — that once went unnoticed may now, as bruises, be hard to miss.


Sometimes, unexplained bruises, or blood spots under the skin that look like bruises, can point a finger at more serious medical conditions, including:

  • effects of medications or supplements — aspirin, anticoagulants (blood thinners), corticosteroids, and dietary supplements, such as fish oil, ginkgo, ginger, and garlic
  • a bleeding or clotting disorder
  • nutritional deficiencies of vitamins B12, C, K, or folic acid
  • inflammation of a blood vessel(s)
  • liver disease
  • sepsis — a widespread presence of infection-causing organisms or their toxins in the blood or tissues
  • chronic inflammatory diseases, e.g., lupus
  • certain cancers, including Hodgkin's disease, leukemia, or multiple myeloma

Anytime unusually large and painful bruises appear for no apparent reason, or are severe after only a minor injury, it is important to consult a health care provider. Other reasons to speak with a provider may include bruising easily while also bleeding from the gums, nose, or intestinal tract; a bruise accompanied by swelling and pain, especially if taking a blood-thinning medication; and, bruises that do not show signs of healing after two weeks or those that do not heal completely after four weeks.


If any of these sound familiar, please see a health care provider as soon as possible. If these signs are not familiar, but the unexplained bruises or diabetes is of further concern to you, a talk with a provider can be helpful in figuring things out. At Columbia, call Health Services at Columbia at x4-2284 or log in to Open Communicator for an appointment.

Alice