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Body fat, lean mass percentages associated with HbA1c in adults without diabetes
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In adults without diabetes, increased percentages of total and trunk body fat were associated with an increased likelihood of an HbA1c in the prediabetes range, whereas similar but less consistent associations persisted in those with diagnosed diabetes, according to an analysis of National Health and Nutrition Examination Survey data.
“While decreasing overall body weight is known to improve hyperglycemia, controlled lab studies clearly demonstrate the importance of the composition of that mass,” Julie K. Bower, PhD, MPH, of the Ohio State University College of Public Health, and colleagues wrote in the study background. “That is, a lower proportion of overall mass that is fat or adipose tissue and a higher proportion that is lean mass are independently associated with improved glucose metabolism and beta-cell function.”
Bower and colleagues analyzed data from 11,125 adults participating in the NHANES between 1999 and 2006. Within the cohort, 846 adults had diagnosed diabetes (mean age, 53 years; 51% men; 58% white; mean BMI, 32.9 kg/m²); 10,125 did not have diabetes (mean age, 41 years; 50% men; 71% white; mean BMI, 27.8 kg/m²). Researchers assessed total and abdominal (trunk) percent body fat and lean mass, measured via DXA, and used linear and logistic regression analyses to examine any association between those measurements and HbA1c.
Participants with diabetes had 37% total body fat, 38% trunk fat, 61% total lean mass and 60% trunk lean mass. Those without diabetes had 33% total body fat, 33% trunk fat, 64% total lean mass and 66% trunk lean mass.
Researchers found that associations between body fat percentage and HbA1c varied by age and sex. Men without diabetes aged 40 years or younger had a 1.57 times greater odds of having an HbA1c at least 5.7% per 5% increase in total fat percentage (95% CI, 1.28-1.93) and a 1.5 times greater odds per 5% increase in trunk fat percentage (95% CI, 1.25-1.79). For men without diabetes aged at least 40 years, each 5% increase in total body fat percentage and 5% increase in trunk fat percentage was associated with an OR of 1.75 (95% CI, 1.53-2) and 1.69 (95% CI, 1.5-1.91), respectively, for an HbA1c of at least 5.7%, according to the researchers.
Women without diabetes aged 40 years or younger had a 2.01 times greater odds of having an HbA1c of at least 5.7% per 5% increase in total fat percentage (95% CI, 1.6-2.54) and a two times greater odds per 5% increase in trunk fat percentage (95% CI, 1.62-2.47). For women without diabetes aged at least 40 years, each 5% increase in total body fat percentage and 5% increase in trunk fat percentage was associated with an OR of 1.51 (95% CI, 1.37-1.65) and 1.6 (95% CI, 1.47-1.74), respectively, for an HbA1c of at least 5.7%, according to the researchers.
Associations were less consistent in the subpopulation with diagnosed diabetes, the researchers noted. In women, only trunk fat percentage was associated with HbA1c, with each 5% increase associated with a 0.05% higher HbA1c (95% CI, 0.01-0.08) for those aged 40 years or younger, and a 0.11% higher HbA1c for women aged at least 40 years (95% CI, 0.06-0.17). Trunk lean mass percentage was associated with a lower HbA1c only in women with diabetes who were aged 40 years or younger. In men with diabetes, each 5% increase in total body fat was associated with a 0.04% increase in HbA1c (95% CI, 0.01-0.07), but only among men aged 40 years or younger; trunk fat percentage was not associated with HbA1c in men.
The researchers noted that the results demonstrate the importance of reduced fat mass in preventing and managing hyperglycemia.
“Interventions that target both weight loss where warranted and decreasing the proportion of fat in relation to lean mass via resistance training may have the most beneficial impact, particularly for diabetes prevention,” the researcher wrote. – by Regina Schaffer
Disclosure: The researchers report no relevant financial disclosures.
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