(1) Background: Protein stimulates the secretion of glucagon (GCG), which can affect glucose metabolism. This study aimed to analyze the metabolic effect of a high-protein diet (HPD) in the presence or absence of proglucagon-derived peptides, including GCG and GLP-1. (2) Methods: The response to HPD feeding for 7 days was analyzed in mice deficient in proglucagon-derived peptides (GCGKO). (3) Results: In both control and GCGKO mice, food intake and body weight decreased with HPD and intestinal expression of Pepck increased. HPD also decreased plasma FGF21 levels, regardless of the presence of proglucagon-derived peptides. In control mice, HPD increased the hepatic expression of enzymes involved in amino acid metabolism without the elevation of plasma amino acid levels, except branched-chain amino acids. On the other hand, HPD-induced changes in the hepatic gene expression were attenuated in GCGKO mice, resulting in marked hyperaminoacidemia with lower blood glucose levels; the plasma concentration of glutamine exceeded that of glucose in HPD-fed GCGKO mice. (4) Conclusions: Increased plasma amino acid levels are a common feature in animal models with blocked GCG activity, and our results underscore that GCG plays essential roles in the homeostasis of amino acid metabolism in response to altered protein intake.

(1) Background: Proglucagon-derived peptides (PDGPs) including glucagon (Gcg), GLP-1, and GLP-2 regulate lipid metabolism in the liver, adipocytes, and intestine. However, the mechanism by which PGDPs participate in alterations in lipid metabolism induced by high-fat diet (HFD) feeding has not been elucidated. (2) Methods: Mice deficient in PGDP (GCGKO) and control mice were fed HFD for 7 days and analyzed, and differences in lipid metabolism in the liver, adipose tissue, and duodenum were investigated. (3) Results: GCGKO mice under HFD showed lower expression levels of the genes involved in free fatty acid (FFA) oxidation such as Hsl, Atgl, Cpt1a, Acox1 (p < 0.05), and Pparα (p = 0.05) mRNA in the liver than in control mice, and both FFA and triglycerides content in liver and adipose tissue weight were lower in the GCGKO mice. On the other hand, phosphorylation of hormone-sensitive lipase (HSL) in white adipose tissue did not differ between the two groups. GCGKO mice under HFD exhibited lower expression levels of Pparα and Cd36 mRNA in the duodenum as well as increased fecal cholesterol contents compared to HFD-controls. (4) Conclusions: GCGKO mice fed HFD exhibit a lesser increase in hepatic FFA and triglyceride contents and adipose tissue weight, despite reduced β-oxidation in the liver, than in control mice. Thus, the absence of PGDP prevents dietary-induced fatty liver development due to decreased lipid uptake in the intestinal tract.

Objectives: The aim of this study was to compare the outcomes of pancreatic transplantation from pediatric donors younger than 15 years of age to the outcomes of pancreatic transplantation from adult donors. Methods: Sixty patients underwent pancreatic transplantation in our facility from August 2012 to June 2019. These patients were divided into two groups according to the age of the donor: Cases in which the donor was younger than 15 years of age were classified into the PD group (n = 7), while those in which the donor was older than 15 years of age were classified into the AD group (n = 53). The outcomes of pancreas transplantation were retrospectively compared between the two groups. Results: Pancreatic graft survival did not differ between the PD and AD groups. Furthermore, there were no differences in the HbA1c and serum creatinine levels at three months, with good values maintained in both groups. The results of oral glucose tolerance tests (OGTTs) revealed that the blood glucose concentration did not differ between the two groups. However, the serum insulin concentration at 30 min after 75 g glucose loading was significantly higher in the PD group. Conclusion: The outcomes of pancreatic transplantation from pediatric donors may be comparable to those of pancreatic transplantation from adult donors and the insulin secretion ability after transplantation may be better.

Background: Sarcopenia and metabolic deterioration are major health concerns in adults aged ≥ 75 years with type 2 diabetes (T2DM), a population characterized by anabolic resistance, reduced dietary intake, and limited renal reserve. Optimizing protein nutrition may support muscle maintenance in this high-risk group, but clinical evidence for individualized high-protein guidance in the oldest-old population remains limited. Objective: We investigated whether an 18-month dietary intervention improves muscle mass and strength in adults aged ≥ 75 years with T2DM and whether serum amino acid (AA) and hormonal profiles reflect these changes. Methods: In this 18-month, single-arm, prospective intervention study, 44 community-dwelling adults aged ≥ 75 years with T2DM received individualized, dietitian-led nutritional guidance targeting a protein intake of approximately 1.4 g/kg ideal body weight (IBW)/day. Assessments at baseline and every 6 months included body composition, muscle strength, renal function, and fasting serum amino acid and hormonal profiles. Longitudinal changes were analyzed using paired t-tests and linear mixed-effects models. This trial was registered in the UMIN Clinical Trials Registry (UMIN000044687). Results: Skeletal muscle index and grip strength showed significant improvements at specific time points during follow-up (both p < 0.05), while gait speed improved at 6 months. Renal function remained clinically stable (eGFRcreat slope: +0.18 mL/min/1.73 m²/year; eGFRcys slope: −2.97 mL/min/1.73 m²/year), with no significant increase in CKD stage. Changes in glucagon correlated positively and C-peptide negatively with changes in skeletal muscle index, whereas glucagon was inversely associated with grip strength. Serum fibroblast growth factor 21 (FGF21) levels decreased over time, suggesting metabolic adaptation to the intervention. Conclusions: Individualized high-protein nutritional guidance for 18 months improved sarcopenia-related parameters, including skeletal muscle index and grip strength, without clinically significant deterioration of renal function in adults aged ≥ 75 years with T2DM. These findings support the feasibility and safety of protein-focused dietary counseling as a strategy to preserve muscle health in advanced age.

Long-term exposure to a high starch, low-protein diet (HSTD) induces body weight gain and hyperinsulinemia concomitantly with an increase in β-cell mass (BCM) and pancreatic islets number in mice; however, the effect of short-term exposure to HSTD on BCM and islet number has not been elucidated. In the present study, we investigated changes in body weight, plasma insulin levels, BCM and islet number in mice fed HSTD for 5 weeks followed by normal chow (NC) for 2 weeks. BCM and islet number were increased in mice fed HSTD for 5 weeks compared with those in mice fed NC. On the other hand, mice fed HSTD for 5 weeks followed by NC for 2 weeks (SN) showed decreased BCM and insulin levels, compared to mice fed HSTD for 7 weeks, and no significant differences in these parameters were observed between SN and the control NC at 7 weeks. No significant difference in body weight was observed among HSTD, NC and SN fed groups. These results suggest that a high-starch diet induces an increase in BCM in a manner independent of body weight gain, and that 2 weeks of NC feeding is sufficient for the reversal of the morphological changes induced in islets by HSTD feeding.

Objectives: We previously reported a high prevalence of hypovitaminosis D (25OHD < 20 ng/mL) in Japanese pregnant women with threatened premature delivery. This study aimed to assess nutritional status and its relationship with bone-related markers and microarchitecture, as measured using quantitative ultrasonography (QUS), in Japanese women during the perinatal period. Methods: We recruited Japanese women who had just delivered at Fujita Health University Hospital (n = 103, cesarean/vaginal delivery = 50/53, age 33.9 ± 4.9 years). On the third day postpartum, their calcaneal QUS was measured, and fasting blood samples were collected. Results: The mean total energy intake (1720 ± 298 kcal/day) was lower than the normal range for Japanese women (2100 kcal/day). Their calcium intake (446 ± 130 mg/day) was significantly below the recommended daily intake (RDI) in Japan (660 mg/day), with 95% of participants consuming less than the RDI. Although the average vitamin D intake (8.7 ± 1.8 μg/day) met the Japanese RDI (8.5 μg/day), 36% of participants consumed less than the RDI. Calcium intake was positively associated with the intake of lipids, protein, and vitamins A, D, and K. Additionally, calcium intake but not vitamin D intake tended to correlate with serum 25-hydroxyvitamin D (25OHD) levels. The QUS indices showed no significant association with calcium or vitamin D intake. Conclusions: During the perinatal period, Japanese women had low calcium intake and relatively low vitamin D intake, accompanied by reduced 25OHD levels. These findings highlight the need for public health recommendations and policies to promote adequate calcium and vitamin D intake during pregnancy.