Insulin Sensitivity Initially Worsens but Later Improves With Aging in Male C57BL/6N Mice.

Aging is believed to induce insulin resistance in humans. However, when and how insulin sensitivity changes with aging remains unclear in both humans and mice. In this study, groups of male C57BL/6N mice at 9-19 weeks (young), 34-67 weeks (mature adult), 84-85 weeks (presenile), and 107-121 weeks of age underwent hyperinsulinemic-euglycemic clamp studies with somatostatin infusion under awake and nonrestrained conditions. The glucose infusion rates for maintaining euglycemia were 18.4 ± 2.9, 5.9 ± 1.3, 20.3 ± 7.2, and 25.3 ± 4.4 mg/kg/min in young, mature adult, presenile, and aged mice, respectively. Thus, compared with young mice, mature adult mice exhibited the expected insulin resistance. In contrast, presenile and aged mice showed significantly higher insulin sensitivity than mature adult mice. These age-related changes were mainly observed in glucose uptake into adipose tissue and skeletal muscle (rates of glucose disappearance were 24.3 ± 2.0, 17.1 ± 1.0, 25.5 ± 5.2, and 31.8 ± 2.9 mg/kg/min in young, mature adult, presenile, and aged mice, respectively). Epididymal fat weight and hepatic triglyceride levels were higher in mature adult mice than those in young and aged mice. Our observations indicate that, in male C57BL/6N mice, insulin resistance appears at the mature adult stage of life but subsequently improves markedly. These alterations in insulin sensitivity are attributable to changes in visceral fat accumulations and age-related factors.

Assessing Patient Satisfaction Following Sodium Glucose Co-Transporter 2 Inhibitor Treatment for Type 1 Diabetes Mellitus: A Prospective Study in Japan.

INTRODUCTION: In Japan, several sodium glucose co-transporter 2 (SGLT2) inhibitors have been used for type 1 diabetes mellitus as an adjuvant therapy to insulin therapy; however, there are no clinical reports regarding the satisfaction of its use. Therefore, we conducted a survey among patients with type 1 diabetes undergoing treatment using an SGLT2 inhibitor. METHODS: This is a single-arm open-label prospective study including 24 patients with type 1 diabetes who were to be initiated on ipragliflozin treatment between March and August 2019. All participants provided written informed consent. They completed the Diabetes Treatment Satisfaction Questionnaire (DTSQ) for the survey and 3 months of observation after the administration of an SGLT2 inhibitor (50 mg of ipragliflozin), and changes from baseline diabetes treatment satisfaction were evaluated using modified DTSQ scores (five-step evaluation) and were analyzed. RESULTS: The average score for each question on DTSQ significantly increased [mean (standard deviation); 0.25 (0.25) vs 0.83 (0.77), P = 0.004]. Approximately 75% of the patients perceived an improvement in glycemic control over short periods of time. Finally, 54.2% of patients were highly satisfied and would recommend the SGLT2 inhibitor treatment [0.0 (0.0) vs. 0.92 (1.32), P < 0.001]. After the administration of ipragliflozin, reductions in body weight [24.0 (2.9) vs. 23.4 (2.9) kg/m2, P = 0.002], total insulin [39.1 (12.9) vs. 34.3 (12.5) units, P = 0.013], and glycated hemoglobin [7.77 (0.97) vs. 7.40 (0.86) %, P = 0.013] were observed, without any severe side effects. Improvements in glycemic variability indexes were observed through flash glucose monitoring. CONCLUSIONS: SGLT2 inhibitors may improve clinical treatment satisfaction by improving glycemic variability in patients with type 1 diabetes mellitus, while not inducing severe side effects with careful use. TRIAL REGISTRATION: This study is registered with the University Hospital Medical Information Network Clinical Trial Registry (UMIN000040487).

The number of octapeptide repeat affects the expression and conversion of prion protein.

The human prion protein (PrP) has five copies of an octapeptide repeat (OR). The mutant PrP with 6-14 OR causes the genetic form of Creutzfeldt-Jakob disease (CJD). To determine the influence of OR on the conversion of PrP, we examined the conversion efficiency of mouse mutant PrP molecules with 1-16 OR in scrapie-infected cells. The expression level of mutant PrP and the glycoform ratio of the abnormal isoform of PrP (PrP(Sc)) were affected by the number of OR. The conversion efficiency was almost equivalent among mutant PrP molecules with 5-16 OR, whereas that of mutant PrP with 1-4 OR was decreased. The present study suggests that CJD patients with the longer extra OR, who usually show only a trace of PrP(Sc) in the brain, can produce the authentic triplet PrP(Sc) if secondary prion infection occurs.