Gestational Ectopic Hyperparathyroidism: A Case Report of Perioperative and Perinatal Outcomes.

In the realm of obstetric care, discerning the subtle signs of primary hyperparathyroidism (PHPT) amidst common pregnancy symptoms remains a formidable challenge. Our exploration into a case of gestational hypercalcemia peels back the layers of this complexity, revealing the clinical conundrum posed by overlapping gastrointestinal manifestations. The journey from diagnosis through surgical intervention to the resolution of symptoms underscores the importance of vigilance for PHPT in pregnant patients. This case further prompts consideration of gamma-aminobutyric acid (GABA) as a potential piece in the puzzle of persistent symptoms post-calcium normalization, inviting a broader dialogue on the intricacies of parathyroid pathology in pregnancy.

Successful Treatment of Postprandial Hyperinsulinemic Hypoglycemia After Billroth-II Gastrojejunostomy Using Octreotide.

Postprandial hyperinsulinemic hypoglycemia, although rare, is a well-documented complication that can manifest after upper gastrointestinal surgery. Despite its potential for severe morbidity, the underlying pathogenesis and optimal treatment strategies for this condition remain insufficiently understood. This report presents a compelling case of postprandial hypoglycemia following Billroth-II gastrojejunostomy, characterized by a marked increase in postprandial insulin levels, accompanied by the exaggerated response of incretin hormones. The incretin effect in this patient was found to be exceptionally high, measuring at approximately 90%. While nutritional interventions proved ineffective in alleviating the patient's symptoms, the administration of octreotide significantly attenuated the exaggerated postprandial insulin and incretin response, substantially ameliorating both the symptoms and postprandial hypoglycemia. Monthly subcutaneous injections of long-acting repeatable octreotide were initiated, resulting in the complete resolution of symptomatic postprandial hypoglycemia. Although the patient developed acalculous cholecystitis and gallstone cholangitis 2 years after commencing octreotide therapy, she has remained free from symptomatic postprandial hypoglycemia for more than 4 years. Our case underscores the efficacy of somatostatin analogs in the management of postprandial hyperinsulinemia after gastrointestinal surgery, shedding light on the potential involvement of incretin hormones in the pathophysiology of this condition.

A Case of Lymphocytic Infundibulo-neurohypophysitis Exhibiting Spontaneous Regression.

Lymphocytic infundibulo-neurohypophysitis (LINH) is a rare autoimmune inflammatory process that selectively affects the neurohypophysis and the pituitary stalk, typically presenting with central diabetes insipidus (CDI). LINH is considered underdiagnosed because the definitive diagnosis requires invasive pituitary surgery with a high risk of complications. We present a case of CDI resulting from LINH, which was treated with conservative management, eschewing both glucocorticoid treatment and pituitary surgery. At presentation, the hormonal assessment indicated the presence of CDI without anterior pituitary dysfunction. Magnetic resonance imaging revealed stalk thickening without a posterior pituitary bright spot, and anti-rabphilin-3A antibodies were positive in serum. Collectively, we made a diagnosis of LINH. Considering that the patient did not exhibit any symptoms of mass effect, we chose conservative treatment with desmopressin acetate. One year later, the stalk thickening regressed spontaneously without surgical or glucocorticoid treatment, although the posterior pituitary bright spot remained absent, and CDI did not improve. The inflammatory process of LINH is mostly self-limited and recovers spontaneously, whereas life-long desmopressin treatment may be required because of pituitary stalk fibrosis and atrophy. Our case highlights the importance of noninvasive diagnosis and careful follow-up in preventing unnecessary interventions for patients with LINH.

An unusual concomitance of acute heart failure: prolactinoma in a patient with left ventricular dysfunction-a case report.

Background: Heart failure concomitant with prolactinoma is extremely rare. Case summary: We present the case of a 29-year-old man who had acute decompensated heart failure concomitant with visual loss in his right eye. Transthoracic echocardiography indicated severely decreased left ventricular (LV) function. A massive tumour on the sella turcica was detected by brain computed tomography. The findings of the laboratory tests showed hyperprolactinaemia with hypopituitarism, and the antigen test for coronavirus disease 2019 was positive as an incidental finding. Medication for heart failure and cabergoline therapy were started immediately. His LV function significantly improved, and he had no symptoms after a year. Discussion: Prolactinoma in men, which can cause visual loss and hypopituitarism, is frequently substantial when diagnosed. The cardiac manifestation of prolactinoma is uncommon. It is believed that a major contributing component to the pathogenesis of peripartum cardiomyopathy is hyperprolactinaemia. Hyperprolactinaemia may cause endothelial damage and cardiomyocyte dysfunction, eventually resulting in LV dysfunction. The success of LV reverse remodelling may be significantly impacted by heart failure and hormone treatments. Heart failure and endocrine therapy should be administered concurrently to patients who have prolactinoma and congestive heart failure.

Resolution of Visual Field Defect in Macroprolactinoma After Treatment With Cabergoline.

We report the case of a 49-year-old woman presenting with amenorrhea and progressive visual field defect for one month. Endocrinological workup revealed a high concentration of serum prolactin, and magnetic resonance imaging (MRI) showed pituitary macroadenoma with extrasellar extension as well as compression of optic nerves. Treatment with a dopamine agonist, cabergoline, for eight weeks led to the resolution of the visual field defect accompanied by a rapid decrease in the serum prolactin level. Follow-up MRI three months after the initial diagnosis revealed alleviation of visible mechanical compression of the optic chiasm by the tumor. We considered that the absence of retinal nerve damage and prompt initiation of cabergoline contributed to the rapid recovery of the visual acuity.

Comorbidity-associated glutamine deficiency is a predisposition to severe COVID-19.

SARS-CoV-2 vaccinations have greatly reduced COVID-19 cases, but we must continue to develop our understanding of the nature of the disease and its effects on human immunity. Previously, we suggested that a dysregulated STAT3 pathway following SARS-Co-2 infection ultimately leads to PAI-1 activation and cascades of pathologies. The major COVID-19-associated metabolic risks (old age, hypertension, cardiovascular diseases, diabetes, and obesity) share high PAI-1 levels and could predispose certain groups to severe COVID-19 complications. In this review article, we describe the common metabolic profile that is shared between all of these high-risk groups and COVID-19. This profile not only involves high levels of PAI-1 and STAT3 as previously described, but also includes low levels of glutamine and NAD+, coupled with overproduction of hyaluronan (HA). SARS-CoV-2 infection exacerbates this metabolic imbalance and predisposes these patients to the severe pathophysiologies of COVID-19, including the involvement of NETs (neutrophil extracellular traps) and HA overproduction in the lung. While hyperinflammation due to proinflammatory cytokine overproduction has been frequently documented, it is recently recognized that the immune response is markedly suppressed in some cases by the expansion and activity of MDSCs (myeloid-derived suppressor cells) and FoxP3+ Tregs (regulatory T cells). The metabolomics profiles of severe COVID-19 patients and patients with advanced cancer are similar, and in high-risk patients, SARS-CoV-2 infection leads to aberrant STAT3 activation, which promotes a cancer-like metabolism. We propose that glutamine deficiency and overproduced HA is the central metabolic characteristic of COVID-19 and its high-risk groups. We suggest the usage of glutamine supplementation and the repurposing of cancer drugs to prevent the development of severe COVID-19 pneumonia.

A case of systemic lupus erythematosus complicated by subclinical Cushing's syndrome: case report.

An 18-year-old female was diagnosed with subclinical Cushing's syndrome (CS) due to a left adrenal adenoma. When she was 20 years old, she developed lupus nephritis. She was treated with high-dose prednisolone (PSL) and soon developed the symptoms of CS. When she was 25 years old, we evaluated her serum glucocorticoid level while she continued to take oral PSL. The result suggested her CS was affected by both the oral PSL and the endogenous cortisol secreted by the adrenocortical adenoma, which was therefore resected. Seven months after the operation, the patient's body weight was decreasing, and her SLE remained in clinical remission. CS complicated by SLE is rare, and the decision to surgically remove an adrenal tumor in such a case is even more rare.

Signaling between pancreatic ß cells and macrophages via S100 calcium-binding protein A8 exacerbates ß-cell apoptosis and islet inflammation.

Chronic low-grade inflammation in the pancreatic islets is observed in individuals with type 2 diabetes, and macrophage levels are elevated in the islets of these individuals. However, the molecular mechanisms underlying the interactions between the pancreatic ß cells and macrophages and their involvement in inflammation are not fully understood. Here, we investigated the role of S100 calcium-binding protein A8 (S100A8), a member of the damage-associated molecular pattern molecules (DAMPs), in ß-cell inflammation. Co-cultivation of pancreatic islets with unstimulated peritoneal macrophages in the presence of palmitate (to induce lipotoxicity) and high glucose (to induce glucotoxicity) synergistically increased the expression and release of islet-produced S100A8 in a Toll-like receptor 4 (TLR4)-independent manner. Consistently, a significant increase in the expression of the S100a8 gene was observed in the islets of diabetic db/db mice. Furthermore, the islet-derived S100A8 induced TLR4-mediated inflammatory cytokine production by migrating macrophages. When human islet cells were co-cultured with U937 human monocyte cells, the palmitate treatment up-regulated S100A8 expression. This S100A8-mediated interaction between islets and macrophages evoked ß-cell apoptosis, which was ameliorated by TLR4 inhibition in the macrophages or S100A8 neutralization in the pancreatic islets. Of note, both glucotoxicity and lipotoxicity triggered S100A8 secretion from the pancreatic islets, which in turn promoted macrophage infiltration of the islets. Taken together, a positive feedback loop between islet-derived S100A8 and macrophages drives ß-cell apoptosis and pancreatic islet inflammation. We conclude that developing therapeutic approaches to inhibit S100A8 may serve to prevent ß-cell loss in patients with diabetes.

Distribution and hormonal characterization of primary murine L cells throughout the gastrointestinal tract.

AIMS/INTRODUCTION: Glucagon-like peptide-1 (GLP-1) secreted from enteroendocrine L cells is an incretin that potentiates insulin secretion and is already applied in therapies for type 2 diabetes. However, detailed examination of L cells throughout the gastrointestinal tract remains unclear, because of difficulties in purifying scattered L cells from other cells. In the present study, we identified characteristics of L cells of the upper small intestine (UI), the lower small intestine (LI) and the colon using glucagon-green fluorescent protein-expressing mice that express GFP driven by the proglucagon promoter. MATERIALS AND METHODS: The localization and density of primary L cells were evaluated by anti-green fluorescent protein antibody reactivity. GLP-1 content, messenger ribonucleic acid (mRNA) expression levels and secretion in purified L cells were measured. RESULTS: The number of L cells significantly increased toward the colon. In contrast, the GLP-1 content and secretion from L cells were higher in the UI than in the LI and colon. L cells from the UI and LI expressed notably high mRNA levels of the transcription factor, islet 1. The mRNA expression levels of peptide YY in L cells were higher in the LI than in the UI and colon. The mRNA expression levels of gastric inhibitory polypeptide in L cells from the UI were significantly higher compared with those from the LI and colon. CONCLUSIONS: L cells show different numbers and characteristics throughout the gut, and they express different mRNA levels of transcription factors and gastrointestinal hormones. These results contribute to the therapeutic application of promoting GLP-1 release from L cells for the treatment of type 2 diabetes.

Rapid exacerbation of lymphocytic infundibuloneurohypophysitis.

RATIONALE: Lymphocytic hypophysitis is a relatively rare autoimmune disease defined by lymphocytic infiltration to the pituitary. Its rarity and wide spectrum of clinical manifestations make clarification of the pathology difficult. Here, we describe a case we examined from the primary diagnosis to final discharge, showing the serial progression of lymphocytic infundibuloneurohypophysitis (LINH) to panhypopituitarism with extrapituitary inflammatory invasion in a short period, and responding favorably to high-dose glucocorticoid treatment. PATIENT CONCERNS: Polyuria, General fatigue and Nausea/Vomiting. DIAGNOSES: Central diabetes insipidus (CDI), Lymphocytic infundibuloneurohypophysitis (LINH). INTERVENTIONS: Desmopressin acetate, High-dose glucocorticoid (GC) treatment. OUTCOMES: He was prescribed desmopressin acetate and subsequently discharged. A month later, he revisited our hospital with general fatigue and nausea/vomiting. A screening test disclosed hypopituitarism with adrenal insufficiency. MRI revealed expanded contrast enhancement to the peripheral extrapituitary lesion. He received high-dose GC treatment and the affected lesion exhibited marked improvement on MRI, along with the recovery of the anterior pituitary function. LESSONS: This case demonstrates the potential for classical LINH to develop into panhypopituitarsim. We consider this is the first documentation of approaching the cause of atypical LINH with progressive clinical course from the pathological viewpoint.

Long-Chain Free Fatty Acid Receptor GPR120 Mediates Oil-Induced GIP Secretion Through CCK in Male Mice.

Free fatty acid receptors GPR120 and GPR40 are involved in the secretion of gut hormones. GPR120 and GPR40 are expressed in enteroendocrine K cells, and their activation induces the secretion of the incretin glucose-dependent insulinotropic polypeptide (GIP). However, the role of these receptors in fat-induced GIP secretion in vivo and the associated mechanisms are unclear. In this study, we investigated corn oil-induced GIP secretion in GPR120-knockout (GPR120-/-) and GPR40-knockout (GPR40-/-) mice. Oil-induced GIP secretion was reduced by 50% and 80% in GPR120-/- and GPR40-/- mice, respectively, compared with wild-type mice. This was not associated with a significant difference in K-cell number or GIP content in K cells, nor messenger RNA levels of the lipid receptor GPR119, nor bile acid receptors TGR5 and farnesoid X receptor. GPR120-/- and GPR40-/- mice also exhibited substantially decreased levels of cholecystokinin (CCK), a hormone from I cells that promotes bile and pancreatic lipase secretion, and this decrease was associated with impaired gallbladder contraction. Notably, treatment with a CCK analog resulted in recovery of oil-induced GIP secretion in GPR120-/- mice but not in GPR40-/- mice. These results indicate that corn oil-induced GIP secretion from K cells involves both GPR120 and GPR40 signaling pathways, and GPR120-induced GIP secretion is indirectly mediated by CCK.

Inhibition of Gastric Inhibitory Polypeptide Receptor Signaling in Adipose Tissue Reduces Insulin Resistance and Hepatic Steatosis in High-Fat Diet-Fed Mice.

Gastric inhibitory polypeptide receptor (GIPR) directly induces energy accumulation in adipose tissue in vitro. However, the importance of the direct effect of GIPR signaling on adipose tissue in vivo remains unclear. In the current study, we generated adipose tissue-specific GIPR knockout (GIPRadipo-/-) mice and investigated the direct actions of GIP in adipose tissue. Under high-fat diet (HFD)-fed conditions, GIPRadipo-/- mice had significantly lower body weight and lean body mass compared with those in floxed GIPR (GIPRfl/fl) mice, although the fat volume was not significantly different between the two groups. Interestingly, insulin resistance, liver weight, and hepatic steatosis were reduced in HFD-fed GIPRadipo-/- mice. Plasma levels of interleukin-6 (IL-6), a proinflammatory cytokine that induces insulin resistance, were reduced in HFD-fed GIPRadipo-/- mice compared with those in HFD-fed GIPRfl/fl mice. Suppressor of cytokine signaling 3 (SOCS3) signaling is located downstream of the IL-6 receptor and is associated with insulin resistance and hepatic steatosis. Expression levels of SOCS3 mRNA were significantly lower in adipose and liver tissues of HFD-fed GIPRadipo-/- mice compared with those of HFD-fed GIPRfl/fl mice. Thus, GIPR signaling in adipose tissue plays a critical role in HFD-induced insulin resistance and hepatic steatosis in vivo, which may involve IL-6 signaling.

Chronic primary adrenal insufficiency after unilateral adrenonephrectomy: A case report.

RATIONALE: Unilateral adrenalectomy as part of surgical resection of renal cell carcinoma (RCC) is not thought to increase the risk of chronic adrenal insufficiency, as the contralateral adrenal gland is assumed to be capable of compensating for the lost function of the resected gland. However, recent studies have indicated that adrenalectomy might cause irreversible impairment of the adrenocortical reserve. We describe a case of chronic primary adrenal insufficiency in a 68-year-old man who previously underwent unilateral adrenonephrectomy, which was complicated by severe postoperative adrenal stress that involved cardiopulmonary disturbance and systemic infection. PATIENT CONCERNS: A 68-year-old Japanese man presented with weight loss of 6 kg over a 4-month period, and renal biopsy confirmed a diagnosis of RCC. He underwent adrenonephrectomy for the RCC, but developed postoperative septic shock because of a retroperitoneal cystic infection and ventricular fibrillation that was induced by vasospastic angina. The patient was successfully treated using antibiotics and percutaneous coronary intervention, and was subsequently discharged with no apparent complications except decreased appetite and general fatigue. However, his appetite and fatigue did not improve over time and he was readmitted for an examination. DIAGNOSES: The workup revealed a markedly elevated adrenocorticotropic hormone (ACTH) level (151.4 pg/mL, normal: 7-50 pg/mL) and a mildly decreased morning serum cortisol level (6.4 mg/mL, normal: 7-28 mg/mL). In addition to the patient's clinical symptoms and laboratory results, the results from ACTH and corticotropin-releasing hormone stimulation tests were used to make a diagnosis of primary adrenal insufficiency. INTERVENTIONS: Treatment was initiated using oral prednisolone (20 mg), which rapidly resolved his symptoms. At the 1-year follow-up, the patient had a markedly decreased serum cortisol level (2.0 mg/mL) with an ACTH level that was within the normal range (44.1 pg/mL) before his morning dose of prednisolone, which confirmed the diagnosis of chronic primary adrenal insufficiency. LESSONS: Clinicians must be aware of chronic adrenal insufficiency as a possible complication of unilateral adrenalectomy, especially when patients who underwent unilateral adrenalectomy experience severe adrenal stress.

Eplerenone improves carotid intima-media thickness (IMT) in patients with primary aldosteronism.

Primary aldosteronism (PA) is associated with a higher rate of cardiovascular events than essential hypertension. Although adrenalectomy has been reported to reduce carotid intima-media thickness (IMT) in patients with PA, the effects of the selective aldosterone blocker, eplerenone, on vascular damage in these patients remains unclear. To evaluate the effects of eplerenone on vascular status in PA patients, we sequentially measured carotid IMT (using computer software to calculate an average IMT for accurate and reproducible evaluation) in 22 patients including 8 patients treated by unilateral adrenalectomy and 14 patients treated with eplerenone for 12 months. Patients who underwent adrenalectomy showed significant reductions in aldosterone concentration (from 345 ± 176 pg/mL to 67 ± 34 pg/mL; P<0.01) and IMT (from 0.67 ± 0.07 mm to 0.63 ± 0.09 mm; P<0.05) 6 months after surgery. Patients treated with eplerenone showed significant reductions in IMT from baseline (0.75 ± 0.10 mm) to 6 (0.71 ± 0.11 mm; P<0.05) and 12 (0.65 ± 0.09 mm; P<0.01) months, although plasma aldosterone level increased significantly, from 141 ± 105 pg/mL to 207 ± 98 pg/mL (P<0.05). Eplerenone treatment of patients with PA reduces blood pressure, increases serum potassium level, and improves vascular status. Carotid IMT may be a useful marker for evaluating the effectiveness of eplerenone in patients with PA.

Enteral supplementation with glutamine, fiber, and oligosaccharide modulates incretin and glucagon-like peptide-2 secretion.

AIMS/INTRODUCTION: A dietary supplementation product enriched with glutamine, dietary fiber and oligosaccharide (GFO) is widely applied for enteral nutrition support in Japan. The aim of the present study was to evaluate the effects of GFO ingestion on secretion of incretins, gastric inhibitory polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), and glucagon-like peptide-2 (GLP-2). MATERIALS AND METHODS: We carried out a cross-over study involving 20 healthy Japanese volunteers. The participants received GFO or 17 g of glucose, the equivalent carbohydrate in GFO as the control. Plasma glucose, serum insulin, and plasma total GIP, total GLP-1 and total GLP-2 levels during GFO or glucose loading were determined. RESULTS: GFO loading produced significantly higher plasma GLP-1 levels at 30 min and 60 min, area under the curve-GLP-1 value, and area under the curve-GLP-2 value after administration compared with those by glucose loading. In contrast, plasma GIP levels at both 30 and 60 min, and area under the curve-GIP value after glucose loading were significantly higher than those after GFO loading. CONCLUSIONS: These results show that GFO ingestion stimulates GLP-1 and GLP-2 secretion, and reduces GIP secretion compared with glucose ingestion. Therefore, GFO could have an intestinotrophic effect as well as an ameliorating effect on metabolic disorders through modification of release of gut hormones.

Fatty acid-binding protein 5 regulates diet-induced obesity via GIP secretion from enteroendocrine K cells in response to fat ingestion.

Gastric inhibitory polypeptide (GIP) is an incretin released from enteroendocrine K cells in response to nutrient intake, especially fat. GIP is one of the contributing factors inducing fat accumulation that results in obesity. A recent study shows that fatty acid-binding protein 5 (FABP5) is expressed in murine K cells and is involved in fat-induced GIP secretion. We investigated the mechanism of fat-induced GIP secretion and the impact of FABP5-related GIP response on diet-induced obesity (DIO). Single oral administration of glucose and fat resulted in a 40% reduction of GIP response to fat but not to glucose in whole body FABP5-knockout (FABP5(-/-)) mice, with no change in K cell count or GIP content in K cells. In an ex vivo experiment using isolated upper small intestine, oleic acid induced only a slight increase in GIP release, which was markedly enhanced by coadministration of bile and oleic acid together with attenuated GIP response in the FABP5(-/-) sample. FABP5(-/-) mice exhibited a 24% reduction in body weight gain and body fat mass under a high-fat diet compared with wild-type (FABP5(+/+)) mice; the difference was not observed between GIP-GFP homozygous knock-in (GIP(gfp/gfp))-FABP5(+/+) mice and GIP(gfp/gfp)-FABP5(-/-) mice, in which GIP is genetically deleted. These results demonstrate that bile efficiently amplifies fat-induced GIP secretion and that FABP5 contributes to the development of DIO in a GIP-dependent manner.

Free fatty acid receptor GPR120 is highly expressed in enteroendocrine K cells of the upper small intestine and has a critical role in GIP secretion after fat ingestion.

Gastric inhibitory polypeptide (GIP) is an incretin secreted from enteroendocrine K cells in response to meal ingestion. Recently free fatty acid receptor G protein-coupled receptor (GPR) 120 was identified as a lipid sensor involved in glucagon-like peptide-1 secretion. However, Gpr 120 gene expression and its role in K cells remain unclear, partly due to difficulties in separation of K cells from other intestinal epithelial cells. In this study, we purified K cells using GIP-green fluorescent protein (GFP) knock-in mice, in which K cells can be visualized by GFP fluorescence. GFP-positive cells (K cells) were observed in the small intestine but not in the stomach and colon. K cell number and GIP content in K cells were significantly higher in the upper small intestine than those in the lower small intestine. We also examined the expression levels of several free fatty acid receptors in K cells. Among free fatty acid receptors, GPR120 was highly expressed in the K cells of the upper small intestine compared with the lower small intestine. To clarify the role of GPR120 on K cells in vivo, we used GPR120-deficient mice (GPR120(-/-)). GPR120(-/-) exhibited significantly lower GIP secretion (75% reduction, P < .01) after lard oil ingestion compared with that in wild-type mice. Consistently, pharmacological inhibition of GPR120 with grifolic acid methyl ether in wild-type mice significantly attenuated lard oil-induced GIP secretion. In conclusion, GPR120 is expressed abundantly in K cells of the upper small intestine and plays a critical role in lipid-induced GIP secretion.

Chronic reduction of GIP secretion alleviates obesity and insulin resistance under high-fat diet conditions.

Gastric inhibitory polypeptide (GIP) exhibits potent insulinotropic effects on ß-cells and anabolic effects on bone formation and fat accumulation. We explored the impact of reduced GIP levels in vivo on glucose homeostasis, bone formation, and fat accumulation in a novel GIP-GFP knock-in (KI) mouse. We generated GIP-GFP KI mice with a truncated prepro-GIP gene. The phenotype was assessed in heterozygous and homozygous states in mice on a control fat diet and a high-fat diet (HFD) in vivo and in vitro. Heterozygous GIP-GFP KI mice (GIP-reduced mice [GIP(gfp/+)]) exhibited reduced GIP secretion; in the homozygous state (GIP-lacking mice [GIP(gfp/gfp)]), GIP secretion was undetectable. When fed standard chow, GIP(gfp/+) and GIP(gfp/gfp) mice showed mild glucose intolerance with decreased insulin levels; bone volume was decreased in GIP(gfp/gfp) mice and preserved in GIP(gfp/+) mice. Under an HFD, glucose levels during an oral glucose tolerance test were similar in wild-type, GIP(gfp/+), and GIP(gfp/gfp) mice, while insulin secretion remained lower. GIP(gfp/+) and GIP(gfp/gfp) mice showed reduced obesity and reduced insulin resistance, accompanied by higher fat oxidation and energy expenditure. GIP-reduced mice demonstrate that partial reduction of GIP does not extensively alter glucose tolerance, but it alleviates obesity and lessens the degree of insulin resistance under HFD conditions, suggesting a potential therapeutic value.