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Arterial norepinephrine concentration inversely, independently associated with insulin clearance
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Whole-body insulin clearance rate in individuals with obesity and metabolic syndrome is inversely and independently associated with arterial norepinephrine concentration, according to recent study findings published in the Journal of Clinical Endocrinology & Metabolism.
“This cross-sectional study shows that within a cohort of metabolic syndrome subjects, elevated levels of sympathetic activity are associated with reduced insulin clearance, which may contribute to the hyperinsulinemia of obesity,” Nora E. Straznicky, PhD, MPH, of Baker IDI Heart and Diabetes Institute in Melbourne, Australia, told Endocrine Today. “Hemodynamic alterations and insulin resistance are two putative mechanisms that may link elevated norepinephrine levels to reduced insulin clearance.”
Nora E. Straznicky
Straznicky and colleagues analyzed data from 31 men and 27 women with obesity and metabolic syndrome to determine the relationship between insulin clearance and resting sympathetic nervous system activity.
They found an inverse relationship between insulin clearance and arterial norepinephrine concentration (P=.0006), whole-body norepinephrine spill-over rate (P=.01) and augmentation index (AI; P=.005), whereas there was a positive association between insulin clearance and insulin sensitivity — both Matsuda insulin sensitivity index (P=.04) and euglycemic clamp-derived insulin sensitivity value (P=.02).
There was a positive association between arterial norepinephrine concentration and LDL cholesterol (P=.004), nonesterified fatty acids (P=.01), fasting insulin (P=.02) and homeostasis model assessment-insulin resistance (P=.03), and an inverse association with Matsuda insulin sensitivity index (P=.04).
Nineteen percent of the variance in insulin clearance was explained by arterial norepinephrine concentration.
“In summary, we have demonstrated for the first time that [sympathetic nervous system] activity, assessed by arterial norepinephrine concentration, is independently and inversely associated with insulin clearance rate in obese individuals with metabolic syndrome,” the researchers wrote. “Prospective studies are required to establish the chronology of change in insulin clearance during weight gain and development of insulin resistance in humans. It is also relevant to examine whether sympathoinhibition during lifestyle interventions is mechanistically involved in the enhancement of insulin clearance observed following weight loss and exercise interventions and whether pharmacological sympathoinhibition has beneficial effects on insulin clearance.” – by Amber Cox
For more information:
Nora E. Straznicky, PhD, MPH, can be reached at Baker IDI Heart & Diabetes Institute, PO Box 6492, St. Kilda Road Central, Melbourne VIC 8008 Australia; email: nora.straznicky@bakeridi.edu.au.
Disclosure: See the full study for a complete list of the researchers’ relevant financial disclosures.
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