Continuous glucose monitoring in a patient with insulinoma presenting with unawareness of postprandial hypoglycemia.

Summary: Unawareness of postprandial hypoglycemia for 5 years was identified in a 66-year-old man at a local clinic. The patient was referred to our hospital because of this first awareness of hypoglycemia (i.e. lightheadedness and impaired consciousness) developing after lunch. In a 75 g oral glucose tolerance test, the plasma glucose concentration was decreased to 32 mg/dL (1.8 mmol/L) at 150 min with relatively high concentrations of insulin (8.1 µU/mL), proinsulin (70.3 pmol/L), and C-peptide (4.63 ng/mL). In a prolonged fasting test, the plasma glucose concentration was decreased to 43 mg/dL (2.4 mmol/L) at 66 h with an insulin concentration of 1.4 µU/mL and a C-peptide concentration of 0.49 ng/mL. Computed tomography showed an 18 mm hyperenhancing tumor in the uncinate process of the pancreas. A selective arterial calcium stimulation test showed an elevated serum insulin concentration in the superior mesenteric artery. The patient was then diagnosed with insulinoma and received pancreaticoduodenectomy. Continuous glucose monitoring (CGM) using the Dexcom G6 system showed unawareness of hypoglycemia mainly during the daytime before surgery. When the sensor glucose value was reduced to 55 mg/dL (3.1 mmol/L), the Dexcom G6 system emitted an urgent low glucose alarm to the patient four times for 10 days. Two months after surgery, an overall increase in daily blood glucose concentrations and resolution of hypoglycemia were shown by CGM. We report a case of insulinoma with unawareness of postprandial hypoglycemia in the patient. The Dexcom G6 system was helpful for assessing preoperative hypoglycemia and for evaluating outcomes of treatment by surgery. Learning points: Insulinoma occasionally leads to postprandial hypoglycemia. The CGM system is useful for revealing the presence of unnoticed hypoglycemia and for evaluating treatment outcomes after surgical resection. The Dexcom G6 system has an urgent low glucose alarm, making it particularly suitable for patients who are unaware of hypoglycemia.

Recurrent distal cholangiocarcinoma and humoral hypercalcemia of malignancy: report of a rare case and literature review.

A 61-year-old Japanese woman presented with epigastric pain and jaundice. Imaging showed the presence of primary distal cholangiocarcinoma (DCC). A subtotal stomach-preserving pancreaticoduodenectomy was performed, followed by chemotherapy using S-1. However, second-line chemotherapy with gemcitabine and cis-diamminedichloroplatinum was required for the treatment of hepatic metastasis of the DCC 3 months following the surgery. Nine months after the surgery, the serum calcium and parathyroid hormone-related peptide concentrations were high, at 16.5 mg/dL and 28.7 pmol/L, respectively, which suggested the presence of humoral hypercalcemia of malignancy (HHM) secondary to the DCC. Moreover, marked leukocytosis, with a white blood cell count of 40,400/µL, was also present. The patient died 11 months after the diagnosis of DCC. Because hypercalcemia of malignancy is associated with a poor prognosis, and HHM and leukocytosis caused by DCC are very rare, we have presented the present case in detail and provide a review of the existing literature.

A case of NASH with genetic predisposition successfully treated with an SGLT2 inhibitor: a possible involvement of mitochondrial dysfunction.

Summary: In this study, we herein describe a 47-year-old Japanese woman who manifested inheritable non-alcoholic steatohepatitis (NASH) and severe dyslipidemia. Interestingly, her NASH progression was ameliorated by treatment with a sodium-glucose co-transporter 2 (SGLT2) inhibitor. This inheritability prompted us to comprehensively decode her genomic information using whole-exome sequencing. We found the well-established I148M mutation in PNPLA3 as well as mutations in LGALS3 and PEMT for her NASH. Mutations in GCKR may contribute to both NASH and dyslipidemia. We further mined gene mutations potentially responsible for her manifestations that led to the identification of a novel M188fs mutation in MUL1 that may be causally associated with her mitochondrial dysfunction. Our case may provide some clues to better understand this spectrum of disease as well as the rationale for selecting medications. Learning points: While the PNPLA3 I148M mutation is well-established, accumulation of other mutations may accelerate susceptibility to non-alcoholic steatohepatitis (NASH). NASH and dyslipidemia may be intertwined biochemically and genetically through several key genes. SGLT2 inhibitors emerge as promising treatment for NASH albeit with interindividual variation in efficacy. Genetic background may explain the mechanisms behind the variation. A novel dysfunctional mutation in MUL1 may lead to metabolic inflexibilities through impaired mitochondrial dynamics and function.

A case of early-onset diabetes with impaired insulin secretion carrying a PAX6 gene Gln135* mutation.

Summary: A paired homeodomain transcription factor, PAX6 (paired-box 6), is essential for the development and differentiation of pancreatic endocrine cells as well as ocular cells. Despite the impairment of insulin secretion observed in PAX6-deficient mice, evidence implicating causal association between PAX6 gene mutations and monogenic forms of human diabetes is limited. We herein describe a 33-year-old Japanese woman with congenital aniridia who was referred to our hospital because of her uncontrolled diabetes with elevated hemoglobin A1c (13.1%) and blood glucose (32.5 mmol/L) levels. Our biochemical analysis revealed that her insulin secretory capacity was modestly impaired as represented by decreased 24-h urinary C-peptide levels (38.0 µg/day), primarily explaining her diabetes. Intriguingly, there was a trend toward a reduction in her serum glucagon levels as well. Based on the well-recognized association of PAX6 gene mutations with congenital aniridia, we screened the whole PAX6 coding sequence, leading to an identification of a heterozygous Gln135* mutation. We tested our idea that this mutation may at least in part explain the impaired insulin secretion observed in this patient. In cultured pancreatic ß-cells, exogenous expression of the PAX6 Gln135* mutant produced a truncated protein that lacked the transcriptional activity to induce insulin gene expression. Our observation together with preceding reports support the recent attempt to include PAX6 in the growing list of genes causally responsible for monogenic diabetes. In addition, since most cases of congenital aniridia carry PAX6 mutations, we may need to pay more attention to blood glucose levels in these patients. Learning points: PAX6 Gln135* mutation may be causally associated not only with congenital aniridia but also with diabetes. Blood glucose levels may deserve more attention in cases of congenital aniridia with PAX6 mutations. Our case supports the recent attempt to include PAX6 in the list of MODY genes, and Gln135* may be pathogenic.

Current status of low-density lipoprotein cholesterol for primary prevention of coronary artery disease in late-stage elderly persons with type 2 diabetes mellitus: A retrospective, single-center study.

AIMS/INTRODUCTION: The importance of low-density lipoprotein cholesterol (LDL-C) in the primary prevention of cardiovascular disease has recently been reported in the population aged ≥75 years with hypercholesterolemia. Therefore, the current status of LDL-C management for primary prevention of coronary artery disease in patients aged ≥75 years with type 2 diabetes mellitus was investigated. MATERIALS AND METHODS: A total of 124 patients aged ≥75 years who had type 2 diabetes mellitus, but no coronary artery disease, were investigated. The patients' background characteristics, LDL-C, glycemic status, ankle-brachial index and cardio-ankle vascular index were compared between patients taking and not taking LDL-C-lowering agents, such as hydroxymethylglutaryl-CoA reductase inhibitors (statins) and ezetimibe. The details of the antihyperlipidemic and antidiabetic agents used in the present study were also examined. RESULTS: LDL-C was significantly lower in patients taking LDL-C-lowering agents (LDLCLT[+]) than in patients not taking them (LDLCLT[-]), although LDL-C was maintained <120 mg/dL in both groups (93.0 mg/dL vs 102.1 mg/dL). Approximately half of the cases in the LDLCLT(+) group received moderate-intensity statins, with pitavastatin being the most prescribed statin. Glycated hemoglobin was significantly lower in the LDLCLT(+) group than in the LDLCLT(-) group (6.9% vs 7.3%). Sodium-glucose transporter 2 inhibitors were more frequently used in the LDLCLT(+) group than in the LDLCLT(-) group. The ankle-brachial index/cardio-ankle vascular index did not differ between the groups. CONCLUSION: Low-density lipoprotein cholesterol was properly managed for primary prevention of coronary artery disease in patients aged ≥75 years with type 2 diabetes mellitus regardless of the presence or absence of LDL-C-lowering agents.

Serial assessments of anterior pituitary hormones in a case of mixed histiocytosis representing Langerhans cell histiocytosis overlapping with Erdheim-Chester disease.

SUMMARY: A 61-year-old man developed central diabetes insipidus caused by mixed histiocytosis (MH) representing Langerhans cell histiocytosis overlapping with Erdheim-Chester disease. Bone, skin, vascular, and retroperitoneal involvements were also observed. Dynamic hormonal testing showed normal responses for anterior pituitary hormones, except for impaired secretion of growth hormone (GH). MRI of the brain showed thickening of the pituitary stalk with slightly reduced signal hyperintensity in the posterior pituitary lobe on T1-weighted imaging. During 2 years of follow-up without radical treatment for MH, imaging studies suggested extension of vascular and retroperitoneal involvements. In contrast, brain MRI did not show any particular interval changes, except for the disappearance of hyperintense signalling in the posterior pituitary lobe. Moreover, no other anterior pituitary dysfunctions beyond GH deficiency emerged during the 2 years of follow-up. The natural history of MH in this case is described, focusing on serial assessments of pituitary functions using dynamic tests. LEARNING POINTS: Erdheim-Chester disease and Langerhans cell histiocytosis overlapping as MH was described, focusing on pituitary functions. MH caused both GH deficiency and central diabetes insipidus. Despite a lack of radical therapy for MH, no other anterior pituitary dysfunctions emerged for 2 years. Radiological images showed no particular interval changes in pituitary stalk lesions, while vascular and retroperitoneal involvements extended.

Acute-onset type 1 diabetes mellitus caused by nivolumab in a patient with advanced pulmonary adenocarcinoma.

A case of acute-onset type 1 diabetes mellitus concomitant with pneumonitis and vitiligo is described.