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Weight change trajectory affects insulin metabolism
Adults without diabetes at any given BMI are more likely to have poorer insulin metabolism if they had a high or increasing BMI trajectory in the preceding 12 years vs. those who had a normal BMI trajectory, according to findings from an Australian study.
“Body weight at any given point in time is informative, but doesn’t tell the whole story,” Erin I. Walsh, PhD, a postdoctoral fellow at the Centre for Research on Ageing, Health and Wellbeing at Australian National University College of Health and Medicine, told Endocrine Today. “When considering the health implications of overweight, it isn't just someone's current BMI that is important. Someone who is in the process of losing or gaining weight can have different insulin metabolism than someone who maintains their weight.”
Walsh and colleagues at the Baker Heart and Diabetes Institute in Melbourne, Australia, analyzed data from 532 middle-aged (aged 40 to 45 years at baseline) and older adults (aged 60 to 65 years at baseline) randomly recruited to participate in the Personality and Total Health Through Life study, a longitudinal study investigating aging, health, cognition and other characteristics for 12 years. Participants provided blood samples and underwent BMI measurements for at least two waves of the study and did not have type 2 diabetes. Researchers assessed plasma glucose, insulin, insulin resistance, insulin sensitivity and beta-cell function and used latent class analysis and linear models to analyze the association between BMI trajectory (defined as constant normal, constant high, increase and decrease) during the 12 years with markers of insulin metabolism.
Among middle-aged adults, researchers found that, at any given BMI, plasma insulin levels were 107% higher (P < .01), insulin resistance was 104% greater (P < .01) and beta-cell function was 28% higher (P < .01) if preceded by a constant high BMI trajectory vs. normal BMI trajectory.
“Preceding trajectory also significantly interacted with current BMI for these outcomes, such that the impact of each unit of BMI was 20% greater on plasma insulin (P = .01) and 19% greater on insulin resistance (P = .02) in the ‘constant high’ than in the ‘constant normal’ trajectory,” the researchers wrote.
Researchers found that a decreasing trajectory in BMI was not independently associated with any blood measurement; however, preceding “decrease” trajectory interacted with BMI, with each unit of BMI associated with an 11% decrease in plasma insulin (P = .02), 10.92% decrease in insulin resistance (P = .02) and 4% decrease in beta-cell function (P = .01) compared with constant normal BMI trajectory.
Among older adults at any given BMI, plasma insulin was 40% higher (P = .01) and insulin resistance was 40% greater (P = .03) if preceded by constant high vs. normal BMI trajectory, according to researchers. There were no between-group differences for older adults in the decreasing and constant normal BMI trajectory groups.
In both middle-aged and older adults, the increasing BMI trajectory was associated with higher plasma insulin level, insulin resistance and beta-cell function for middle-aged adults only, according to researchers.
“Unsurprisingly, results support the conclusion that high body weight is associated with elevated blood glucose levels and impaired insulin function,” the researchers wrote. “Of much greater interest, however, are the novel findings that naturalistic weight change (rather than change induced by dietary or surgical intervention in a particularly at-risk population) is associated with insulin metabolism in adult humans, and that trajectories of weight gain and high weight maintenance have distinguishable impacts on insulin metabolism.”
Walsh said further investigation of weight change during tighter time periods is needed.
“This study followed body weight every 4 years, so sampling more frequently would give a more precise picture of what's going on,” Walsh said. “Also, a more precise range of biomarkers of insulin metabolism could be very informative.” – by Regina Schaffer
For more information:
Erin I. Walsh, PhD, can be reached at the Centre for Research on Ageing, Health and Wellbeing, Australian National University College of Health and Medicine, Research School of Population Health, 54 Mills Road, Acton, ACT, 2601; email: erin.walsh@anu.edu.au.
Disclosures: The authors report no relevant financial disclosures.