Variability in activity may precede diabetic foot ulceration

OBJECTIVE: To evaluate the role of activity in the development of neuropathic foot ulceration in individuals with diabetes. RESEARCH DESIGN AND METHODS: We evaluated the first 100 consecutive individuals with diabetes (95.0% male, aged 68.5 +/- 10.0 years with concomitant neuropathy, deformity, and/or a history of lower-extremity ulceration/partial foot amputation) enrolled in an ongoing prospective longitudinal activity study. Subjects used a high-capacity continuous computerized activity monitor. Data were collected continuously over a minimum of 25 weeks (or until ulceration) with daily activity units expressed as means +/- SD. RESULTS: Eight subjects ulcerated during the evaluation period of 37.1 +/- 12.3 weeks. The average daily activity was significantly lower in individuals who ulcerated compared with individuals who did not ulcerate (809.0 +/- 612.2 vs. 1,394.5 +/- 868.5, P = 0.03). Furthermore, there was a large difference in variability between groups. The coefficient of variation was significantly greater in the ulceration group compared with the no ulceration group (96.4 +/- 50.3 vs. 44.7 +/- 15.4%, P = 0.0001). In the 2 weeks preceding the ulcerative event, the coefficient of variation increased even further (115.4 +/- 43.0%, P = 0.02), but there was no significant difference in average daily activity during that period (P = 0.5). CONCLUSIONS: The results of this study suggest that individuals with diabetes who develop ulceration may actually have a lower overall activity than their counterparts with no ulceration, but the quality of that activity may be more variable. Perhaps modulating the "peaks and valleys" of activity in this population through some form of feedback might prove to reduce risk for ulceration in this very-high-risk population.