Prevalence of lower extremity diseases associated with normal glucose levels, impaired fasting glucose, and diabetes among U.S. adults aged 40 or older

Abstract

Background Peripheral arterial disease (PAD) and peripheral neuropathy (PN) are serious complications of diabetes, but early detection and intervention may reduce this morbidity. The degree to which PAD and PN develop before diabetes diagnosis has not been established among a representative sample of U.S. adults. Objective To compare the prevalence of lower extremity diseases (LEDs) among U.S. adults aged 40 or older with previously diagnosed diabetes, undiagnosed diabetes, impaired fasting glucose, and normal glucose levels. Research design and methods We analyzed cross-sectional data of a nationally representative sample of 3607 U.S. adults from the 1999–2004 National Health and Nutrition Examination Surveys (NHANES). Subjects were divided into four groups on the basis of their fasting plasma glucose (FPG) levels and interview responses: normal glucose levels (FPG < 100 mg/dl), impaired fasting glucose (IFG; FPG 100–125 mg/dl), undiagnosed diabetes (FPG ≥ 126 and no self-reported diabetes), and diagnosed diabetes. PN was assessed by monofilament testing at three sites on each foot and defined as ≥1 insensate area. PAD was defined as an ankle-brachial blood pressure index <0.9. Any LED was defined as the presence of PAD or PN or a history of non-healing ulcer or amputation. Results The prevalence of PN was lowest among persons with normal glucose (10.5%) and IFG (11.9%) and highest among those with undiagnosed (16.6%) and diagnosed diabetes (19.4%). PAD prevalence was also lowest among persons with normal glucose (3.9%), similar among those with IFG (5.4%), and significantly higher among those with undiagnosed (9.2%) and diagnosed diabetes (7.5%). Any LED was present in about 27% of persons with both undiagnosed diabetes and diagnosed diabetes. Conclusions LED prevalence was nearly as high among persons with previously undiagnosed diabetes as among those with diagnosed diabetes, but it was not appreciably higher among persons with impaired fasting glucose than among those with normal glucose levels. These results suggest that LED detection efforts should be focused on persons with diabetes, including those with undiagnosed diabetes.