Insulinoma Causing Hypoglycemia in a Patient with Type 2 Diabetes

Insulinoma in Patients with Diabetes- A Systematic Review of Previously Reported Cases

Introduction

Paradoxical co-existence of insulinoma and diabetes is extremely rare. Although a few case reports addressed this association, a comprehensive study elucidating this relationship has been lacking. We performed a systematic review of published cases of insulinoma in diabetes.

Methods

We conducted a literature search using PubMed and Google Scholar, employing various combinations of the following terms: 'insulinoma', 'diabetes', 'nesidioblastosis', 'endogenous hyperinsulinism', 'hypoglycaemia', and 'hyperglycaemia' (from January 1900 to January 30, 2024). Exclusion criteria included non-English publications, duplicate articles, reports lacking sufficient data, cases of endogenous hyperinsulinemic hypoglycaemia other than insulinoma, and inaccessible articles. Statistical analysis was performed using appropriate methods.

Results

Sixty patients were considered for the final analysis. Mean age was 61 ± 15 years (range: 17-96 years) with a slight female preponderance; 88.3% had type-2 diabetes with a median duration of 8 years. The median delay in diagnosis of insulinoma was 6 months. Median blood glucose varied from 30.5 mg/dL to 235 mg/dL, with a mean HbA1c of 5.6 ± 1.3% (range: 2.9%-8.2%). Critical sampling data were available in 75% of cases. The median size of the insulinoma was 2 cm. Furthermore, 5.2% of insulinomas were extra-pancreatic. Among pancreatic insulinomas, 14.5% were multi-focal. One-third of cases were malignant. Surgical resection was done in 70.9% of cases, while 40% received drug therapy and 12.7% received both, with 20.7% overall mortality. Malignant insulinoma (P = 0.007), micro-angiopathic (P = 0.018) and macro-angiopathic complications (P = 0.039), and other co-morbidities (P = 0.009) were associated with unfavourable prognosis, while being overweight and obese (P = 0.020) at presentation was associated with favourable prognosis.

Conclusion

This first systematic review provides insights into the uniqueness of insulinoma in diabetes.

Metastatic insulinoma presenting after bariatric surgery in a patient diagnosed with MEN1

Insulinomas are uncommon neuroendocrine tumors and metastatic disease is extremely rare. We report a patient with metastatic insulinoma associated with multiple endocrine neoplasia type 1 presenting with hypoglycemia following sleeve gastrectomy. Potential causes of hypoglycemia include dumping syndrome, noninsulinoma pancreatogenous hypoglycemia syndrome, and rarely insulinoma. MEN1‐associated insulinomas have a higher recurrence rate.

Case Report: Insulinoma Co-Existing With Type 2 Diabetes - Advantages and Challenges of Treatment With Endoscopic Ultrasound-Guided Radiofrequency Ablation

The coexistence of insulinoma and type 2 diabetes is rare and the diagnostic process is often challenging. Continuous glucose monitoring system devices, which are more readily available nowadays, provide a useful tool for the diagnosis and evaluation of treatment response. Curative surgery is often the mainstay of treatment for insulinoma. Here, we report a Chinese patient with insulinoma diagnosed simultaneously with type 2 diabetes. His insulinoma was managed with endoscopic ultrasound guided-radiofrequency ablation (EUS-RFA) and the patient achieved complete resolution of hypoglycaemic episodes. The case illustrates that while EUS-RFA is an emerging non-invasive treatment modality for pancreatic lesions, limitations exist especially when histological confirmation is essential.

Challenge of coexisting type 2 diabetes mellitus and insulinoma: a case report

Background

Insulinomas are rare clinical entities, but concurrent diabetes mellitus is even more uncommon, and the combination is easily missed. Recurrent hypoglycemia could be misconstrued as improved glycemic control. We present an unusual patient with type 2 diabetes and neuroglycopenia, with apparent improved glycemic control due to an insulinoma.

Case presentation

A 54-year-old mixed ancestry man with a positive family history of type 2 diabetes mellitus was diagnosed with type 2 diabetes mellitus and hypertension 8 years prior to admission. He presented with episodes of abnormal behavior and hypoglycemia. Inappropriately high insulin and C-peptide concentrations were identified at the time of hypoglycemia. Despite poor adherence to his diabetic treatment, he had no target organ damage relating to diabetes, and his hemoglobin A1c (HbA1c) was 5.3%. A diagnosis of insulinoma was made, and he was started on diazoxide, with endoscopic ultrasound revealing a possible lesion in the pancreatic tail measuring 12 mm × 12 mm. A fine-needle aspiration biopsy could not be performed due to overlying splenic arteries and the risk of vascular perforation. An intraoperative ultrasound confirmed a 15 mm × 10 mm tumor in the pancreatic tail, necessitating a partial pancreatectomy and splenectomy, which were curative. A well-differentiated intermediate grade 2 pancreatic neuroendocrine tumor producing insulin was confirmed on histopathology.

Conclusions

Recurrent, progressive hypoglycemia and improved glycemic control in a diabetic, without an alternative explanation, may suggest an insulinoma. Insulinomas that exist with type 1 diabetes mellitus, particularly malignant insulinomas, must have escaped autoimmune attack through lack of autoantigen expression. Computed tomography on its own may be insufficiently sensitive for diagnosis of insulinomas, whereas endoscopic and intraoperative ultrasonography may improve the identification of the culprit lesion.

Malignant Insulinoma with Multiple Liver Metastases and Hypercalcitoninemia in a Patient with Type 2 Diabetes Mellitus Presenting as Recurrent Episodes of Diaphoresis due to Severe Hypoglycemia

Insulinoma is an insulin-producing pancreatic neuroendocrine tumor that can be malignant in about 10% of cases. Locoregional invasion, lymph node metastases, or remote metastases are the main criteria of malignant insulinoma. Its incidence in patients with pre-existing diabetes mellitus (DM) is exceptionally rare. In this report, we describe a 66-year-old man with long-standing type 2 DM who presented with recurrent episodes of diaphoresis due to severe hypoglycemia despite the withdrawal of insulin therapy, hypercalcitoninemia, and biochemical and radiological findings suggestive of metastatic malignant insulinoma. Unfortunately, after few days of diazoxide treatment, edema, hypotension, oliguria, and water retention were observed, patient's clinical status deteriorated rapidly, and he died in our department from acute renal failure.

Sudden 'cure' of type two diabetes due to pancreatic insulinoma: A case report

Insulinomas are rare tumors of the islet cells of the pancreas and are the most common cause of endogenous hyperinsulinism. Although they usually present with symptoms of hypoglycemia, sometimes they can have vague symptoms. We present the case of a 62-year-old diabetic female who was diagnosed with a large insulinoma after being investigated for the 'cure' of her diabetes. We also review the literature regarding insulinomas in patients with diabetic. A 62-year-old, obese woman with type 2 diabetes mellitus was initially investigated for an unexplained normalization of her blood glucose levels after the cessation of antidiabetic medication due to an episode of severe hypoglycemia. She remained without antidiabetics for three months maintaining normoglycemia, and thereafter, she started experiencing frequent but less severe hypoglycemic episodes. She did not change her diet habits or level of activity and did not lose any weight. The patient underwent further investigation with a supervised 72 h fasting test, which resulted in the biochemical diagnosis of endogenous hyperinsulinism. Imaging studies revealed the presence of a large insulinoma in the head of the pancreas. Finally, the patient underwent a pylorus preserving Whipple procedure, which reversed the aforementioned 'normalization' of glucose levels and the underlying diabetes mellitus reappeared. Insulinomas are rare tumors causing hypoglycemia. Even more rarely are found in diabetic patients, making the diagnosis more challenging and probably delayed, as the symptoms are masked by the presence of diabetes, thereby leading to a more advanced disease diagnosis.

Revisiting the IGF-1R as a breast cancer target

The type I insulin-like growth factor-1 receptor is a well-described target in breast cancer and multiple clinical trials examining insulin-like growth factor-1 receptor have been completed. Unfortunately, monoclonal antibodies and tyrosine kinase inhibitors targeting insulin-like growth factor-1 receptor failed in phase III breast clinical trials for several reasons. First, insulin-like growth factor-1 receptor antibody therapy resulted in hyperglycemia and metabolic syndrome most likely due to disruption of insulin-like growth factor-1 homeostasis and subsequent growth hormone elevation. Growth hormone elevation induces insulin resistance, hence a subsequent elevation of insulin and the potential for activation of insulin receptor. Second, the insulin-like growth factor-1 receptor and insulin receptor are highly homologous in amino acid sequence, structure, and function. These two receptors bind insulin, insulin-like growth factor-1 and insulin-like growth factor-2, to regulate glucose uptake and other cellular functions. Hybrid receptors composed of one chain of insulin-like growth factor-1 receptor and insulin receptor also participate in signaling. Third, since all the monoclonal antibodies were specific for insulin-like growth factor-1 receptor, any pathophysiologic role for insulin receptor was not inhibited. While the insulin-like growth factor-1 receptor tyrosine kinase inhibitors effectively inhibited both insulin-like growth factor-1 receptor and insulin receptor, these drugs are not being further developed likely due to their metabolic toxicities. Insulin-like growth factor-1/2 neutralizing antibodies are still being studied in early phase clinical trials. Perhaps a more comprehensive strategy of targeting the insulin-like growth factor-1 receptor network would be successful. For example, targeting receptor, ligand and downstream signaling molecules such as phosphatidylinositol 3′-kinase or particularly the insulin receptor substrate adapter proteins might result in a complete blockade of insulin-like growth factor-1 receptor/insulin receptor biological functions.

Association of Insulinoma and Type 2 Diabetes Mellitus

The association of diabetes mellitus and insulinoma is unusual. We are reporting the case of a 58 years old patient having diabetes mellitus type 2 for several years. This patient was well balanced with oral anti-diabetic treatment. However, the diagnosis of insulinoma was discussed due to recent episodes of hypoglycemia that persisted even after stopping the treatment. Abdominal CT allowed the topographic diagnosis. The patient underwent a caudal pancreatectomy. Furthermore, the postoperative period shows that the diabetes mellitus requires the oral anti-diabetic treatment and basal insulin have to be stable. Then, the occurrence of hypoglycemia in the diabetic mellitus type 2 and, especially the persistence after discontinuation of therapy, suggest the unusual diagnosis of insulinoma as illustrated in our observation.

Exposure to excess insulin (glargine) induces type 2 diabetes mellitus in mice fed on a chow diet

We have previously shown that insulin plays an important role in the nutrient-induced insulin resistance. In this study, we tested the hypothesis that chronic exposure to excess long-acting insulin (glargine) can cause typical type 2 diabetes mellitus (T2DM) in normal mice fed on a chow diet. C57BL/6 mice were treated with glargine once a day for 8 weeks, followed by evaluations of food intake, body weight, blood levels of glucose, insulin, lipids, and cytokines, insulin signaling, histology of pancreas, ectopic fat accumulation, oxidative stress level, and cholesterol content in mitochondria in tissues. Cholesterol content in mitochondria and its association with oxidative stress in cultured hepatocytes and β-cells were also examined. Results show that chronic exposure to glargine caused insulin resistance, hyperinsulinemia, and relative insulin deficiency (T2DM). Treatment with excess glargine led to loss of pancreatic islets, ectopic fat accumulation in liver, oxidative stress in liver and pancreas, and increased cholesterol content in mitochondria of liver and pancreas. Prolonged exposure of cultured primary hepatocytes and HIT-TI5 β-cells to insulin induced oxidative stress in a cholesterol synthesis-dependent manner. Together, our results show that chronic exposure to excess insulin can induce typical T2DM in normal mice fed on a chow diet.

GLP-1 and glucagon secretion from a pancreatic neuroendocrine tumor causing diabetes and hyperinsulinemic hypoglycemia

CONTEXT

Glucagon-like peptide-1 (GLP-1) is a gut peptide that promotes insulin release from pancreatic β-cells and stimulates β-cell hyperplasia. GLP-1 secretion causing hypoglycemia has been described once from an ovarian neuroendocrine tumor (NET) but has not been reported from a pancreatic NET (pNET).

OBJECTIVE

A 56-yr-old male with a previous diagnosis of diabetes presented with fasting hypoglycemia and was found to have a metastatic pNET secreting glucagon. Neither the primary tumor nor metastases stained for insulin, whereas the resected normal pancreas showed histological evidence of islet cell hyperplasia. We provide evidence that GLP-1 secretion from the tumor was the cause of hyperinsulinemic hypoglycemia.

METHODS

GLP-1 levels were determined in the patient, and immunohistochemistry for GLP-1 was performed on the tumor metastases. Ex vivo tissue culture and a bioassay constructed by transplantation of tumor into nude mice were performed to examine the tumor secretory products and their effects on islet cell function.

RESULTS

The patient had high levels of glucagon and GLP-1 with an exaggerated GLP-1 response to oral glucose. Immunohistochemistry and primary tissue culture demonstrated secretion of glucagon and GLP-1 from the tumor metastases, whereas insulin secretion was almost undetectable. Ex vivo coculture of the tumor with normal human islets resulted in inhibition of insulin release, and transplanted mice developed impaired glucose tolerance.

CONCLUSIONS

This is the first description of glucagon and GLP-1 secretion from a metastatic pNET causing sequential diabetes and hypoglycemia. Hypoglycemia was caused by insulin secretion from hyperplastic β-cells stimulated by tumor-derived GLP-1.

Type 2 diabetes mellitus in a patient with malignant insulinoma manifesting following surgery

BACKGROUND

Insulinomas, although they are rare, are the most common of pancreatic islet cell tumours. The incidence is estimated at only four per million person-years and only 5-12% of reported cases are malignant. Distinction between malignant and benign tumours can only be made by the presence of metastasis, as there are no specific morphologic, biochemical or genetic features distinguishing them. Most patients with malignant insulinoma have lymph node or liver metastases and, rarely, bone involvement. The coincidence of insulinoma and diabetes mellitus is an extremely rare condition and reported only in a few cases.

CASE REPORT

We report a 45-year-old woman who was diagnosed with insulinoma on the basis of clinical and laboratory findings and endoscopic examination. Histopathological diagnosis revealed well-differentiated endocrine carcinoma of the pancreas with lymph node metastases. The case was accepted as malignant insulinoma and the patient underwent surgery. Interestingly, hyperglycaemia occurred after the removal of the insulinoma, with the requirement for insulin in the post-operative 3 weeks, which was changed to oral anti-diabetic agents as a permanent treatment. The patient is still being treated with oral anti-diabetic agents. We think that the patient might have had diabetes mellitus, because of insulin resistance that developed with a high-caloric intake stimulated by hypoglycaemia, and which had been masked for many years, but manifested overtly after removal of the tumour.

CONCLUSIONS

Although this is a rare condition, clinicians should bear in mind that insulinomas may exist together with diabetes mellitus, and it is important to have this suspicion when considering the perioperative approach and for the prevention of morbidities.

A rare cause of hypoglycemia in a type 2 diabetic patient: insulinoma

Recurrent episodes of hypoglycemia in patients with diabetes are often associated with the ongoing treatment regimen. However, despite changes in treatment modalities, assessment of the causes of hypoglycemia in nondiabetic patients in the presence of severe and recurrent hypoglycemia is very important. The treatment that had been provided for 6 years in a 67-year-old female patient with type 2 diabetes mellitus was discontinued due to hypoglycemic episodes that presented for the previous 2 years. The patient experienced persistent hypoglycemia after cessation of the treatment and was hospitalized for further examination. Spontaneous hypoglycemia with a final diagnosis of insulinoma was established following histopathologic evaluation and was relieved postoperation. Insulinoma is rarely encountered as a cause of hypoglycemia in patients with type 2 diabetes. Insulin-secreting tumors should be considered where hypoglycemic episodes occur despite discontinuation of insulin and other antidiabetic treatment with endogenous hyperinsulinemia being noncompliant with the blood glycemic levels.

Insulinoma presenting as postprandial hypoglycaemia

Although insulinoma commonly presents as fasting hypoglycaemia it can rarely present as postprandial hypoglycaemia. We describe a case of insulinoma presenting as postprandial hypoglycaemia and type 2 diabetes mellitus (T2DM). A 60-year-old man presented with a 6 year history of postprandial hypoglycaemic symptoms. A diagnosis of T2DM was made using a standard oral glucose tolerance test to which patient's postprandial hypoglycaemia was attributed. He was given dietetic advice for postprandial hypoglycaemia and was followed up routinely. After 2 years, hypoglycaemic symptoms worsened by exercise and delayed meals. A number of supervised fasting glucose measurements failed to demonstrate biochemical hypoglycaemia. His insulin, c-peptide and pro-insulin levels were mildly elevated but plasma glucose levels were normal. A CT scan showed 20 mm lesion in the pancreas which was confirmed as insulinoma with pancreatic arterial calcium stimulation studies. Laparoscopic resection confirmed benign insulinoma and hypoglycaemia resolved. Our case illustrates the importance of considering insulinoma as a cause of postprandial hypoglycaemia.

Metastatic insulinoma in a patient with type 2 diabetes mellitus: case report and review of the literature

Pancreatic neuroendocrine tumors (NETs) are extremely rare, and although insulinomas are the commonest, less than 10% of insulinomas are malignant. Most patients with insulinomas present with neuroglycopenic symptoms and weight gain attributable to insulin excess. Here, we report a case where a 67-year-old lady with a background history of type 2 diabetes mellitus and breakthrough hyperinsulinism who presented with coma. The biochemical profile revealed features typical of insulinoma, and CT and endosonography confirmed a pancreatic tumor with large volume right-sided liver metastases (biopsy confirming a neuroendocrine tumor). The patient underwent successful one-step RO surgical resection, distal pancreatectomy, splenectomy, and right hepatectomy, and 9 months postoperatively, she remains free of recurrent disease. She remains a diabetic.

Overtly manifested diabetes mellitus after resection of insulinoma

Insulinoma is the most common cause of endogenous hyperinsulinemic hypoglycemia in adults. However, the coincidence of insulinoma and diabetes is extremely uncommon. We describe a rare, but very interesting case of diabetes mellitus which was masked by insulinoma and was overtly manifest after the removal of the insulinoma.