Insulin resistance and autonomic function in traumatic lower limb amputees

Abstract

This study examined plasma insulin response to oral glucose load and autonomic nervous system activity in male lower limb amputees (n = 52) aged 50-65 years, compared to matched controls (n = 53). The groups had similar body mass index, blood pressure and plasma lipid levels. The amputees had higher mean fasting plasma insulin levels (18.4 +/- 9.7 (SD) versus 13.7 +/- 5.1 mU/l, p = 0.005) and during an oral glucose tolerance test (OGTT) (1 h levels 88.1 +/- 45.3 versus 62.1 +/- 42.7, p = 0.016) with similar plasma glucose levels, indicating insulin resistance. At baseline with the subjects supine, there were no group differences in low- or high-frequency power of heart rate variability or in plasma levels of norepinephrine (NE) or epinephrine (EPI). In response to orthostasis, the groups had similarly increased plasma NE levels. During the OGTT, amputees had significantly larger increments in low-frequency power than did controls (2.2 +/- 1.3 versus 1.6 +/- 0.9 (beats/min)2 respectively, p< 0.01) and plasma NE levels increased significantly in amputees (1595 +/- 849 versus 1941 +/- 986 pM, p = 0.0008) but not in controls. At 1 h after glucose administration, plasma EPI levels were decreased significantly from baseline in both groups; at both 1 and 2 h after glucose administration, plasma EPI levels were higher in the amputees than controls. Amputees appear to have a combination of enhanced sympathoneural responsiveness and attenuated suppression of adrenomedullary secretion during glucose challenge. As catecholamines antagonize insulin effects, one possible explanation for insulin resistance in amputees is hyperglycaemia-induced sympathoneural activation and a failure of hyperglycaemia to decrease adrenomedullary secretion.

Increased peripheral vascular resistance in male patients with traumatic lower limb amputation

“…Furthermore, the release and the sensitivity of norepinephrine are increased in this condition [29]. Although the present study did not evaluate sympathetic nerve activity in traumatic lower limb amputees, Peles et al [30] observed an increase in plasma norepinephrine levels in this population. The authors raised the hypothesis that compression caused by the prosthesis and physical overload promotes an increase in sympathetic nerve activity and shear forces, causing endothelial dysfunction and increasing blood pressure levels.…”

Impact of Traumatic Lower Extremity Injuries Beyond Acute Care: Movement-Based Considerations for Resultant Longer Term Secondary Health Conditions

“…97 When compared to uninjured controls with no difference in body mass index, blood pressure, or lipid levels, persons with LL exhibited significantly higher increased fasting plasma insulin levels as well as insulin resistance. 96 Increased plasma insulin levels and insulin resistance are risk factors for atherosclerosis and metabolic syndrome, considered precursors to CVD. The role of psychological stressors in the development of CVD is not well understood; however, psychosocial factors have demonstrated involvement in the pathogenesis of CVD.…”

Prevalence of metabolic syndrome and health-related quality of life in war-related bilateral lower limb amputees

“…Peles et al compared the insulin resistance between lower limb amputees and healthy controls with similar age, body mass index, blood pressure and plasma lipid levels. Amputees were found to have significantly higher fasting plasma insulin levels and insulin response to oral glucose with similar plasma glucose levels [27]. Modan et al also showed increased levels of insulin in amputees compared to healthy controls after adjustment for age, smoking, physical activity, body mass index, mean arterial blood pressure and cholesterol [28].…”