Lower percentages of lean body mass have shown correlation to a higher risk of diabetes in older men.
As patients age, it is inevitable for them to experience metabolic, mental, and physical changes. Risks can become higher for developing health altering conditions, and body composition can start to shift as well. In the aging population, muscle loss, also known as sarcopenia, is becoming a point of concern because it has been linked to the progression of type 2 diabetes. Studies have already established the impact of obesity in patients with type 2 diabetes. A previous demonstration also showed that patients with increased blood glucose levels and diabetes displayed declined lean body mass, leg muscle quality, knee extensor strength, and quicker loss of muscle function. This study took a more in-depth look into lean body mass percentages and gender differences in older adults to assess their relationship with the development of type 2 diabetes.
This longitudinal cohort study extensively evaluated men and women (age range 20-98 years) based on age for a median follow-up of 7 years: participants younger than 60 years old were seen every four years, between 60 and 79 years old every two years, and 80 years old and up were seen annually. To assess glycemic statuses, participants received an oral glucose tolerance test (OGTT), had their blood glucose levels checked, and HbA1c levels observed. To evaluate their body composition, fat mass, fat-free mass, and bone mineral density, researchers used dual x-ray absorptiometry (DXA). For each body composition measure, quartiles were created from the DXA assessments, and baseline characteristics were established and used to compare differences in total lean body mass. Using rigorous analytic methods, cox models accounted for changes in lean body mass during follow-ups. Furthermore, diabetes in these participants was defined as either self-reported history and taking diabetic medications or a fasting blood glucose of 126mg/dL or higher and a two-hour OGTT glucose of 200mg/dL at the same visit or two consecutive visits. Logistic regression was used to investigate the incidence of diabetes by looking at the distribution of the probability of diabetes progression within the quartiles.
The analysis unveiled unexpectedly that men and women with higher absolute total lean body mass and in the highest quartile were associated with a higher risk (HR 1.32, 95% CI. 0.65-2.75, p=0.15) of developing type 2 diabetes. The DXA technology included the liver, lungs, and intestinal tract in its assessment and was not specific to skeletal muscle contractile mass. The actual presence of muscle mass may have been less in participants but possibly not detected correctly. In a study that compared the assessment of body composition between DXA and computed tomography (CT), another method of assessment, it was noted that DXA underestimated abdominal fat mass and overestimated muscle mass from extremities as the weight of the subjects increased. Hydration levels have also been proved to affect the estimation of body composition by this technology. The significant evidence that this study demonstrated was that relatively lower lean body mass with aging was connected to higher incidence rates of type 2 diabetes in men and not in women. Another study, with participants averaging 73 years old, had similar inverse results with higher absolute total lean body mass corresponding to higher incidences of diabetes. Findings from a separate study showed the same reversed relationship with muscle mass and incidence of type 2 diabetes in a younger group of participants (average age of 39 years old.)
The study’s main limitation was not having HbA1c readings available for all participants; it was a new diagnostic criterion during this time. This lack of data may have left room for missed diagnoses of diabetes in participants. Also, to truly gauge how much intermuscular and intramuscular fat is present, which has shown to be related to insulin resistance, further studies using other body composition assessments like CT or magnetic resonance imaging (MRI) are needed. Both options have shown excellent accuracy when discerning muscle and fat areas. Both assessing technologies could give a more clarified evaluation of skeletal muscle mass and adequately explain the relationship between absolute lean body mass and type 2 diabetes development.
- Higher absolute total body mass was associated with a raised incidence of type 2 diabetes development; however, DXA may not have detected the correct percentage of muscle mass
- Older men with lower percentages of total lean body mass showed a higher risk of developing type 2 diabetes than women
- Further studies using alternate body composition assessments are needed to give further insight into the relationship between absolute lean body mass and type 2 diabetes development
Kalyani, Rita R, et al. “The Relationship of Lean Body Mass with Aging to the Development of Diabetes.“ Journal of the Endocrine Society, 2020, doi:10.1210/jendso/bvaa043.
Maya Palmer, PharmD. Candidate, Florida A&M University College of Pharmacy