Unexplained bruises


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,

While everyone is likely to have a bruise at some point in their life, seeing them out of the blue may be a cause for concern. Bruises usually occur when capillaries (the tiny blood vessels in the body) are injured and the blood that flows through them leaks into the surrounding area. The body eventually reabsorbs the blood and the bruise goes away. The list of usual suspects for bruising includes bumping into bedposts or other objects and not remembering, rigorous physical activity (which can cause tiny tears in blood vessels, particularly in athletes and weightlifters), and old age. There could be other underlying causes for frequent bruising, but it’s likely not caused by diabetes. What your husband may be referring to is acanthosis nigricans, a condition in which the skin surrounding folds and creases become thick and dark. This condition has been correlated to the development of type 2 diabetes. If you’ve frequently noticed unexplained bruises or that they don’t heal after a couple of weeks, it might be good idea to talk with your health care provider.

Some people are more likely to bruise than others, so it may be that you’re less likely to notice the injury that caused it. Moreover, as people grow older the skin loses some of the fatty layer that cushions blood vessels against damage, making them more susceptible to bruising. It could be that the minor injuries — especially to the arms and legs — that once went unnoticed may now, as bruises, are harder to miss. It’s also possible that unexplained bruises, or blood spots under the skin that look like bruises, can point to more serious concerns, including:

  • Effects of medications or supplements, such as aspirin, anticoagulants (blood thinners), corticosteroids, and dietary supplements, including fish oil, ginkgo, ginger, and garlic
  • Nutritional deficiencies of vitamins B12, C, K, or folic acid
  • A bleeding or clotting disorder
  • Physical abuse
  • Alcohol abuse
  • Liver disease or cirrhosis
  • Sepsis
  • Cancer

Anytime unusually large and painful bruises appear for no apparent reason, or are severe after only a minor injury, it’s recommended that you speak with a health care provider. If this frequent bruising is accompanied by 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 don’t show signs of healing after two weeks or those that don’t heal completely after four weeks, it’s best to seek medical attention.

Black and blue, if you’re worried about diabetes, there are other warning signs to make note of: increased thirst and urination, extreme hunger, weight loss, fatigue, blurred vision, and frequent infections may result from a high blood-sugar level. In any case, your health care provider may be able to run some tests to help pinpoint the cause of your bruises and offer an appropriate treatment plan.

Best wishes for being bruise-free,

Last updated May 17, 2019
Originally published May 08, 1995

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