Prevention and Early Intervention for Diabetes Foot Problems
3. Causative Factors
Risk Factors for Lower Extremity Amputation (LEA)
Peripheral neuropathy, peripheral vascular disease, and prior foot ulcer are independently associated with risk of LEA
10. A 1996 study of Pima Indians with diabetes confirmed this finding and included the presence of foot deformity as another independent risk factor11. The presence of plantar callus also is highly predictive of subsequent ulceration in patients with diabetic neuropathy and is more predictive of ulceration than increased plantar foot pressures12. Hyperglycemia is an additional risk factor. In a 1996 study, Finnish researchers determined risk factors for amputation in 1,044 middle-aged patients with type 2 diabetes who were followed for up to 7 years. Because the incidence of amputation was similar in both sexes (5.6 percent men and 5.3 percent women), all statistical analyses were carried out combining men and women. This study found that high fasting plasma glucose levels at baseline, high HbA1c, and the duration of diabetes were independently associated with a twofold risk of amputation. Signs of peripheral neuropathy, bilateral absence of vibration sense, and bilateral absence of Achilles tendon reflexes were two times more frequent in patients with amputation than in patients without amputation13.
These findings are supported by the Diabetes Control and Complications Trial (DCCT), a ten-year clinical study that concluded in 1993. The DCCT demonstrated that keeping blood glucose levels as close to normal as possible slows significantly the onset and progression of eye, kidney, and nerve diseases caused by diabetes. The study showed that any sustained lowering of blood glucose helps, even if the person has a history of poor control14.
Causal Pathways for Lower Extremity Amputations (LEA)
A study conducted at the Seattle Veterans Affairs Medical Center examined the causal pathways for LEA in patients with diabetes and identified the most common sequences of events. Seventy-three percent of the amputations in study subjects were a result of the causal sequence of minor trauma, cutaneous ulceration, and wound-healing failure. Estimates of the cumulative proportions of various causes indicated that 86 percent of amputations were attributed to initial minor trauma causing tissue injury15.