Background—
Sarcopenia refers to a decline in skeletal muscle mass and strength associated with aging. Low muscle mass increases risks of physical disability and mortality. Patients with type 2 diabetes are more prone to develop sarcopenia than that of their non-diabetic counterparts. Chronic hyperglycemia and comorbidities are more likely to accelerate the loss of muscle mass and strength, leading to adverse physical functions. Identifying the risks of low muscle mass in type 2 diabetic patients allows early detection of the high-risk patients and application of preventive measure. The purpose of this study was to investigate the prevalence of low muscle mass; its association with diabetes characteristics, body composition, and related complications among type 2 diabetic patients.
Research Question—
We addressed three research questions in this study as follows:
1.What was the prevalence of low muscle mass in patients with type 2 diabetes in a primary care clinic?
2.What were the characteristics of type 2 diabetic patients having low muscle mass comparing with their counterparts having normal muscle mass?
3.What were the correlates for prediction of low muscle mass in patients with type 2 diabetes?
Study/Design Methods—
Participants were 2,404 patients (53.0% male) from a diabetic clinic with age, 63.2±12.9 (mean±SD) years; disease duration, 12.5±7.9 years; and glycosylated hemoglobin (A1C), 7.3±1.1% (Table1). Demographic characteristics, comorbidities, and clinical test results, were obtained in retrospect from the patient’s medical records. Body mass index (BMI) was defined as body mass/body height2 (kg/m2). Appendicular skeletal muscle mass (ASM, kg), skeletal muscle mass index (SMI=ASM/height2 kg/m2), fat mass (kg), and percent body fat (PBF= fat mass/body mass x 100%), were assessed by bioelectrical impedance analysis (Inbody770, Korea). Low muscle mass (LMM) was defined as a SMI below 7.0 kg/m2 for the males and 5.7 kg/m2 for the females.
Statistical / Analytical Methods —
Patients were stratified into the normal muscle mass (NMM) or the LMM group by gender and by SMI criteria. Descriptive statistics was presented as mean and standard deviation for ratio variables, and as percentage for categorical variables. The independent-sample t-test was used to examine the difference between means for ratio data, and χ2 test for categorical data. The prevalence of LMM was analyzed across different age groups and gender. Multivariate logistic regression was used to examine the association between LMM and age, gender, disease duration, BMI, PBF, chronic kidney disease (CKD), and A1C. All analyses were performed using statistic software with the statistical significance level at 0.05.
Results—
The prevalence of LMM was male, 22.7%; female, 34.0%. The age-specific prevalence of LMM was 9.4%, 16.3%, 31.0%, and 54.2% for age 18-<34, 35-<65, 65-<75, and ≥75 years, respectively (Table2). Comparing with the NMM group, the LMM group was older; had more women; longer disease duration; lower PBF, HbA1c, BMI; and higher percentage of CKD stage≥3b (p<0.05). Independent correlates of LMM was being female (1.84, 1.41-2.40); age ≥75 years (5.52, 1.78-17.10) comparing with 18-<35 years; higher A1C: ≥7.0 to <8.0 (0.67, 0.49-0.91) comparing with <7.0; BMI: <18.5 (24.69, 5.70-107.03), ≥23.0 to <25.0 (0.04, 0.02-0.06), and ≥25.0 (0.00, 0.000-0.002) comparing with18.5 to <23; higher PBF: Q2 (5.86, 3.76-9.12), Q3 (34.13, 18.61-62.60), and Q4 (159.71, 75.39-338.35) comparing with Q1 (Table3).
Conclusions—
Over one-fifth of men and one-third of women with type 2 diabetes studied had LMM. LMM increased with advancing age - over one-half by ≥75 years old. Besides old-age and being female, having higher percent body fat increased the risk of LMM. Low BMI predicted higher and high BMI predicted lower risk. Good glycemic control is important for diabetic complication prevention, yet not necessarily for sarcopenia prevention. To prevent or delay sarcopenia among type 2 diabetic patients, routine screening for high percent body fat or low BMI for early sign of LMM is strongly recommended.