Year-long effects of COVID-19 restrictions on glycemic control and body composition in patients with glucose intolerance in Japan: A single-center retrospective study.

AIMS/INSTRUCTION: During the coronavirus disease 2019 (COVID-19) pandemic, the lockdowns in Europe raised concerns about negative effects on glycemic control and body composition in patients with diabetes. In Japan, voluntary-based restrictions were imposed as the declaration of a state of emergency (DSE), whose metabolic consequences have not been fully investigated. We carried out a single-center retrospective study to evaluate changes in glycemic control and body composition in outpatients with glucose intolerance after the DSE. MATERIALS AND METHODS: We enrolled outpatients with glucose intolerance: (i) for whom longitudinal data about body composition were available; (ii) who participated in dietary follow up with nutritionists; and (iii) whose laboratory data included glycated hemoglobin (HbA1c) levels before and after the DSE. RESULTS: Among 415 patients, we found no significant changes in HbA1c overall after the DSE. Bodyweight and fat mass increased significantly, whereas skeletal mass decreased significantly. HbA1c changes after the DSE were significantly correlated with changes in bodyweight and fat mass. In 128 patients whose HbA1c levels increased ≥0.3%, changes in bodyweight and fat mass were significantly larger than those in the other 287 patients. With regard to lifestyle changes, increased snacking was likely to worsen glycemic control (odds ratio 1.76, P = 0.036). CONCLUSIONS: COVID-19 restrictions in Japan had unfavorable metabolic consequences for patients with glucose intolerance, highlighted by increased bodyweight and body fat, and decreased skeletal muscle. In addition, lifestyle changes, such as increased snacking, might worsen glycemic control. Clinical attention and interventions are required to prevent such metabolic changes.

Causal associations between body fat accumulation and COVID-19 severity: A Mendelian randomization study

Previous studies reported associations between obesity measured by body mass index (BMI) and coronavirus disease 2019 (COVID-19). However, BMI is calculated only with height and weight and cannot distinguish between body fat mass and fat-free mass. Thus, it is not clear if one or both of these measures are mediating the relationship between obesity and COVID-19. Here, we used Mendelian randomization (MR) to compare the independent causal relationships of body fat mass and fat-free mass with COVID-19 severity. We identified single nucleotide polymorphisms associated with body fat mass and fat-free mass in 454,137 and 454,850 individuals of European ancestry from the UK Biobank, respectively. We then performed two-sample MR to ascertain their effects on severe COVID-19 (cases: 4,792;controls: 1,054,664) from the COVID-19 Host Genetics Initiative. We found that an increase in body fat mass by one standard deviation was associated with severe COVID-19 (odds ratio (OR)body fat mass = 1.61, 95% confidence interval [CI]: 1.28–2.04, P = 5.51 × 10-5;ORbody fat-free mass = 1.31, 95% CI: 0.99–1.74, P = 5.77 × 10-2). Considering that body fat mass and fat-free mass were genetically correlated with each other (r = 0.64), we further evaluated independent causal effects of body fat mass and fat-free mass using multivariable MR and revealed that only body fat mass was independently associated with severe COVID-19 (ORbody fat mass = 2.91, 95% CI: 1.71–4.96, P = 8.85 × 10-5 and ORbody fat-free mass = 1.02, 95%CI: 0.61–1.67, P = 0.945). In summary, this study demonstrates the causal effects of body fat accumulation on COVID-19 severity and indicates that the biological pathways influencing the relationship between COVID-19 and obesity are likely mediated through body fat mass.