Preserved seasonal variation in glycemic control in patients with type 2 diabetes mellitus during COVID-19: a 3-year-long retrospective cohort study in older adults in Japan.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has changed our lifestyle by imposing restrictions, such as physical distancing. The effect of COVID-19 prevalence on seasonal variations in glycemic control in patients with diabetes mellitus (DM) remains unknown. METHODS: This single-center retrospective cohort study evaluated glycemic control in patients with type 2 DM who visited Sugi Cardiovascular Hospital in December 2021. We evaluated the clinical findings of all patients treated regularly between March 1, 2019, and December 31, 2021, including the periods both before and after the COVID-19 pandemic. All the standard treatments were approved. Furthermore, seasonal changes in hemoglobin A1c (HbA1c) levels were evaluated using stratified analyses based on age. RESULTS: This study analyzed 86 patients (mean age, 69.6 ± 9.2 years; men, 57). Median HbA1c (National Glycohemoglobin Standardization Program [Union of Clinical Chemistry]) levels in spring (March) were 7.70% (interquartile range (IQR):7.23%-8.30%) [60.6 mmol/mol (IQR:55.4-67.2 mmol/mol)], 7.35% (IQR:6.90%-7.90%) [56.8 mmol/mol (IQR:51.9-62.8 mmol/mol)], and 7.50% (IQR:7.10%-8.00%) [58.5 mmol/mol (IQR:54.1-63.9 mmol/mol)] in 2019, 2020, and 2021, respectively. During these periods, HbA1c levels and body mass index (BMI) revealed significant seasonal variations "high in spring" and "low in autumn." Median HbA1c levels in spring (March) and autumn (September) were 7.86% [61.2 mmol/mol] and 7.48% [57.4 mmol/mol] in 2019 (P < 0.001), 7.50% [57.7 mmol/mol] and 7.17% [54.2 mmol/mol] in 2020 (P < 0.001), and 7.61% [58.3 mmol/mol] and 7.19% [53.8 mmol/mol] in 2021 (P < 0.001). Seasonal variations in HbA1c levels and BMI were maintained over the past 3 years, including the pandemic period. None of the patients in this study developed COVID-19 during the study period. CONCLUSIONS: Seasonal variations in glycemic control in patients with DM were not influenced by lifestyle modifications associated with COVID-19. Maintenance of physical activity is necessary to prevent the development of sarcopenia. Moreover, seasonal variations in glycemic metabolism should be considered an independent factor for DM management. Additional extensive multifacility investigations are necessary to corroborate our findings.

Evidence for a positive association between serum carnitine and free testosterone levels in uremic men with hemodialysis.

BACKGROUND AND AIMS: Low free testosterone levels are associated with sexual dysfunction and an increased risk of cardiovascular disease in male hemodialysis patients. Carnitine deficiency is frequently observed in hemodialysis patients as well. However, the relationship between carnitine and testosterone levels remains unknown. In this study, we examined whether carnitine deficiency was independently associated with low free testosterone levels in male hemodialysis patients. METHODS: Nineteen male hemodialysis patients underwent determinations of blood chemistries, including serum levels of free testosterone, carnitine, and pentosidine, one of the well-characterized advanced glycation end products. RESULTS: Mean free testosterone levels in hemodialysis patients were significantly lower than those in healthy controls (4.67±2.69 vs. 9.50±3.67 pg/mL, p<0.001). Univariate analysis revealed that carnitine (p=0.023), pentosidine (inversely, p=0.027), blood glucose (inversely, p=0.032), creatinine (p=0.026) levels, and statin use (inversely, p=0.034) were correlated with free testosterone values. Multiple stepwise regression analysis revealed that carnitine (p=0.001) and statin use (inversely, p=0.002) were the independent determinants of age-adjusted free testosterone levels in hemodialysis patients (r² =0.612). CONCLUSIONS: The present study gives the first evidence that decreased carnitine levels were independently associated with low free testosterone values in male hemodialysis patients. Our study suggests that decreased carnitine levels may be a novel therapeutic target for uremic men with hemodialysis.

Decreased serum carnitine is independently correlated with increased tissue accumulation levels of advanced glycation end products in haemodialysis patients.

AIM: There is accumulating evidence that advanced glycation end products (AGE) play a role in cardiovascular disease (CVD) in patients with haemodialysis (HD). Carnitine deficiency is frequently observed in HD patients, which may also contribute to CVD. In this study, we examined whether carnitine deficiency was independently associated with increased tissue accumulation levels of AGE in HD patients. METHODS: One hundred and twenty-nine HD patients underwent determinations of blood chemistries including serum level of carnitine. Tissue AGE levels were evaluated by measuring skin autofluorescence with an AGE-reader. RESULTS: Serum carnitine levels were significantly lower, while skin AGE levels were significantly higher in HD patients compared with healthy controls (P < 0.001). In univariate analysis, ß(2)-microglobulin (ß(2)-MG) and carnitine (inversely) were correlated with skin AGE levels. Multiple stepwise regression analysis revealed that carnitine levels were one of the independent determinants of skin AGE levels (P = 0.024). When ß(2)-MG-adjusted skin AGE levels were stratified by serum carnitine levels, a statistical significance and dose-response relationship were observed (P = 0.043). Furthermore, skin AGE levels were one of the independent determinants of serum carnitine levels as well (P = 0.012). CONCLUSION: The present study demonstrated that decreased carnitine levels were independently associated with increased skin AGE levels in HD patients. Since carnitine is reported to inhibit the formation of AGE in vitro, our study suggests that supplementation of carnitine may be a therapeutic target for preventing the accumulation of tissue AGE and subsequently reducing the risk of CVD in HD patients.