Does diabetes hide osteoarthritis pain?

Clinical practice and research efforts related to the highly prevalent and disabling disease, osteoarthritis (OA), have long been hampered by an inadequate case definition. Much of the difficulty is due to a lack of agreement between X-rays evidence of OA and a patient's report of pain at that site. Such discordance between reported pain and radiographic evidence of OA has been attributed to several factors. This paper proposes another possible explanation, for at least a portion of such patients. It is hypothesized that an insidiously increasing diabetic neuropathy, particularly in the lower extremity, while first causing some pain, may gradually inhibit the ability to feel pain which might have otherwise been reported by those patients without neuropathy. Many of these patients with early stage glucose dysmetabolism will proceed to develop overt type 2 diabetes; however, the pain-inhibiting neuropathy caused by glucose metabolism dysfunction may manifest long before such a diagnosis. The high prevalence of diabetes and pre-diabetic conditions, especially among the aged population, could mean that a substantial number of individuals with osteoarthritis will have both diseases to varying degrees over time. Validating and quantifying this hypothesized association would be useful to millions of persons and would significantly impact both research and clinical practice dealing with these major diseases of older persons. (C) 2012 Elsevier Ltd. All rights reserved.