The increasing prevalence of sarcopenic obesity is a major public health concern in the aging population and is a likely risk factor for type 2 diabetes mellitus (T2DM).
The present study has prospectively characterized the longitudinal development of obesity, sarcopenia, and type 2 diabetes (T2DM) in 130 adult male rhesus monkeys (NHPs) in order to identify possible early markers and specific risk factors for sarcopenic obesity. Variables followed include % body fat and lean mass by DXA, fasting serum chemistry, HbA1c, and IV glucose tolerance (K glucose 5-20 min).
Serum creatinine was positively related to lean muscle mass measured by DXA in non-diabetic adult NHPs (r=0.6; p<0.001) and was significantly reduced in advanced-aged NHPs (20-29 yrs) compared to young (10-14 yr) or middle-aged (15-19yr) adults (p’s <0.01).Advanced-aged NHPs had 17% less muscle mass, corresponding to a serum creatinine level of 0.8±0.04 mg/dl. Sarcopenic obesity was characterized by a combination of % body fat ≥ 27 and serum creatinine ≤ 0.8 mg/dl, and both were significantly higher in the obese NHPs without sarcopenia (p’s<0.001). Lean muscle mass was significantly lower in NHPs with sarcopenic-obesity with decreased levels of creatinine compared to obese monkeys without low creatinine (p<0.001). NHPs with sarcopenic-obesity had significantly higher fasting plasma glucose, and HbA1c%,and lower glucose tolerance and lower BUN, albumin, total cholesterol, and HDL cholesterol compared to obese NHPs without sarcopenia (all p’s <0.05). Thirty-nine percent of NHPs with obesity and T2DM had sarcopenia compared to 13% in the obesity-only group.
The pathophysiological development of age-associated sarcopenia in NHPs, like the development of obesity and of T2DM, appears to be highly similar to the patterns in humans. These data support the identification of low serum creatinine as a marker for sarcopenic-obesity and as a risk factor for T2DM.