Background: The aim of this study was to investigate the effect of the coronavirus disease (COVID-19) pandemic restrictions on the change in muscle mass in older patients with type 2 diabetes (T2D), who were not infected with COVID-19. Methods: In this retrospective cohort study, data were obtained from outpatients who underwent bioelectrical impedance analysis at least twice before April 2020 and at least once thereafter. Skeletal muscle mass index (SMI, kg/m²) was calculated as appendicular muscle mass (kg) divided by height squared (m²). Change in SMI (kg/m²/year) was calculated as (follow-up SMI—baseline SMI/follow-up period). The differences between the changes in SMI before and after the start of the COVID-19 pandemic were evaluated using paired t test. Results: This study recruited 56 patients, with a mean (SD) age of 75.2 (7.1) years. SMI changed from 6.7 (0.9) to 6.8 (0.9) kg/m² before the COVID-19 pandemic, whereas SMI changed from 6.8 (0.9) to 6.6 (0.9) kg/m² after the start of the COVID-19 pandemic. SMI decreased after the start of the COVID-19 pandemic compared with before the pandemic (−0.117 (0.240) vs. 0.005 (0.289) kg/m²/year, p = 0.049). This decrease was observed in men (−0.159 (0.257) vs. 0.031 (0.325) kg/m²/year, p = 0.038), patients with poor glycemic control (−0.170 (0.264) vs. 0.031 (0.285) kg/m²/year, p = 0.042), and those with a long diabetes duration (−0.153 (0.229) vs. 0.082 (0.291) kg/m², p = 0.049). Conclusions: The COVID-19 pandemic restrictions caused muscle mass loss in older patents with T2D. Actions, including recommendation of exercise and adequate diet intake, are needed to prevent loss of muscle mass.

Context Branched-chain amino acids (BCAA) are substrates for protein synthesis. Although their intake may contribute to an increase in skeletal muscle mass, elevated serum BCAA levels have been reported to be associated with insulin resistance, potentially resulting in decreased skeletal muscle mass. Objective This study aimed to explore the association between elevated serum BCAA levels and longitudinal skeletal muscle loss. Design and Setting A cohort analysis was conducted, in which serum amino acids were analyzed in healthy individuals who underwent a medical health checkup at Kameoka Municipal Hospital (HOZUGAWA study), Japan. Patients Seventy-one participants (37 men and 34 women) underwent follow-up checkups after the baseline visit. The follow-up duration was 1.2 ± .4 years. Main Outcome Measures The relationship between fasting baseline serum BCAA levels and lifestyle factors, body composition, blood test results, dietary history, and changes in skeletal muscle mass was evaluated. Results In both men and women, serum BCAA levels were positively correlated with body weight, body mass index, skeletal muscle mass index (SMI), and serum triglycerides but inversely correlated with serum high-density lipoprotein cholesterol. In men, fasting serum BCAA levels were inversely associated with the rate of change in SMI (adjusted β = −.529, P = .006), and elevated BCAA levels were independently associated with a longitudinal decrease in skeletal muscle mass (odds ratio: 1.740; 95% confidence interval: 1.023-2.960 per 50 nmol/mL serum BCAAs increase). Conclusion Increased circulating BCAAs could be an indicator of skeletal muscle loss in men.

Background: Sarcopenia, characterized by muscle mass decline due to aging or other causes, is exacerbated by decreased estrogen levels after menopause in women. Isoflavones, a class of flavonoids acting on estrogen receptors, may have beneficial effects on metabolic disorders. We examined these effects in ovariectomized mice fed a high-fat, high-sucrose diet (HFHSD). Methods: At 7 weeks old, female C57BL6/J mice (18–20 g, n = 12) underwent bilateral ovariectomy (OVX), and were then fed a high-fat, high-sucrose diet starting at 8 weeks of age. Half of the mice received isoflavone water (0.1%). Metabolic analyses, including glucose and insulin tolerance tests, were conducted. Muscle analysis involved grip strength assays, next-generation sequencing, quantitative RT–PCR, and western blotting of skeletal muscle after euthanizing the mice at 14 weeks old. Additionally, 16S rRNA gene sequence analysis of the gut microbiota was performed. Results: The results demonstrated that isoflavone administration did not affect body weight, glucose tolerance, or lipid metabolism. In contrast, isoflavone-treated mice had higher grip strength. Gene expression analysis of the soleus muscle revealed decreased Trim63 expression, and western blotting showed inactivation of muscle-specific RING finger protein 1 in isoflavone-treated mice. Gut microbiota analysis indicated higher Bacteroidetes and lower Firmicutes abundance in the isoflavone group, along with increased microbiota diversity. Gene sets related to TNF-α signaling via NF-κB and unfolded protein response were negatively associated with isoflavones. Conclusions: Isoflavone intake alters gut microbiota and increases muscle strength, suggesting a potential role in improving sarcopenia in menopausal women.

Background/Objectives: Western-type diets (WDs) damage the intestinal barrier by disrupting the gut microbiota composition and causing inflammation, leading to the development of obesity, type 2 diabetes, and non-alcoholic fatty liver disease. Short-chain fatty acids (SCFAs) are produced by the gut microbiota and found in fermented foods and can stimulate the anti-inflammatory action of type 3 innate lymphoid cells (ILCS3s) in the intestine. This study hypothesised that supplementing miso, a Japanese fermented food, to a WD could increase the levels of SCFAs and thus stimulate ILC3s, decreasing inflammation in the intestine and protecting intestinal barrier integrity. Methods: Mice with RORγt total (KI/KI) or partial (KI/w) knockout were fed a high-fat high-sugar diet (HFHSD) for eight weeks as a model of WD. Half of the mice received miso supplementation in addition to the HFHSD. Weight gain, glucose tolerance and insulin resistance, intestinal barrier integrity, intestinal immunity, and liver condition were assessed. Results: Miso supplementation increased SCFA levels in the small intestine, which stimulated ILC3 function in KI/w mice. Glucose tolerance was improved, intestinal barrier integrity was ameliorated, and mucus production was increased. The level of IL-22 was increased, while pro-inflammatory ILC1s, M1 macrophages, TNF-α, and IL-1β were decreased. Liver condition was not affected. Conclusions: This study demonstrated that miso supplementation influenced several factors involved in inflammation and intestinal barrier integrity by stimulating ILC3s in RORγt heterozygous mice. Moreover, it showed that the number of ILC3s is not the key factor in immune regulation, but rather the ability of ILC3 to produce IL-22 and employ it to control the immune response in the small intestine.