Insulinoma Presenting with Reactive Hypoglycemia: Evaluating the Effect of Tumor Resection via Continuous Glucose Monitoring

Spontaneous hypoglycemia: should we mind the gap? Long-term follow-up of healthy people who met Whipple's triad criteria

CONTEXT

Patients discharged as "healthy" with the symptoms of spontaneous hypoglycemia, commonly known as Whipple's triad, need more attention.

OBJECTIVE

Characterization and long-term follow-up of symptom development in patients with spontaneous hypoglycemia discharged as "healthy". The objective was to ascertain whether any conditions related to the symptoms were diagnosed during the follow-up period.

METHODS

Retrospective analysis of patient data and evaluation of a specific questionnaire on the development of symptoms of spontaneous hypoglycemia. In addition, patient questionnaires were evaluated and primary care physicians were asked about possible diseases not recorded at baseline that occurred during the follow-up period.

SETTING

Center for Endocrinology, Diabetology, and Osteology at the University Hospital Marburg, Inpatient Department, Germany.

PATIENTS

All patients who presented to our center for the 72-hour fast between 2005 and 2018 and were discharged without an internal medicine diagnosis were included.

INTERVENTIONS

Survey by questionnaire, via telephone interview.

MAIN OUTCOME MEASURES

Patient-reported information on current symptoms compared to original symptoms, diagnosis of insulinoma or diabetes mellitus during follow-up, matched with primary care physician data, and metabolic and biometric data such as body mass index (BMI), homeostasis model assessment for insulin resistance (HOMA IR), insulin sensitivity Matsuda Index (ISI-M), and area under the curve.

RESULTS

A total of 41 datasets were evaluated at baseline and 38 patients were followed for an average of approximately 10 years. In total, 61% of respondents still reported the same symptoms as at baseline. No insulinoma was missed in these patients. Only two of the 38 patients developed diabetes mellitus.

CONCLUSION

The high percentage of patients who are discharged as "healthy" and still have symptoms after many years is disturbing. It is possible that the symptoms are not due to low blood glucose. We urge caution with use of the term "healthy". We advocate a multidisciplinary therapeutic approach after an organic cause of hypoglycemia has been ruled out. Psychosomatic treatment seems to be useful. In addition, more research should be conducted on this topic.

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.

Glucagon: Its evolving role in the management of hypoglycemia

More than 10% of the United States population has diabetes, characterized by hyperglycemia. Insulin and other agents used to treat diabetes predispose people to hypoglycemia, which can be life threatening. Glucagon is an emergency medication that can save lives by quickly raising glucose in people who are unconscious or unable to consume glucose due to severe hypoglycemia. Although glucagon has been commercially available since 1960, earlier formulations required reconstitution of a dry powder with diluent immediately prior to injection, due to lack of long-term stability once reconstituted. Glucagon has been underutilized due to the lack of confidence or ability to administer in emergency situations. More recently, new formulations including a nasal powder glucagon and liquid-stable glucagon have become available. This article discusses the evidence surrounding new glucagon formulations compared with the original glucagon emergency kit including ease of use, efficacy, and safety with a focus on important patient counseling points and relevant clinical information on hypoglycemia.

Continuous Glucose Monitoring in Patients With Insulinoma Treated by Endoscopic Ultrasound-Guided Ethanol Injection

OBJECTIVES

The aims of this study were to analyze the continuous glucose monitoring (CGM) profiles of patients with insulinoma before and after treatment with endoscopic ultrasound-guided ethanol injection and assess the value of CGM in curative effect evaluating.

METHODS

We included 8 patients, and CGM was performed for 3 to 5 days before and after treatment.

RESULTS

The proportion of monitoring points at which the glucose level was lower than 3.9 mmol/L after treatment decreased in patient 5 (from 4% to 3%) and patient 8 (from 30% to 12%), whereas the proportion increased in patient 1 (from 1% to 16%), patient 3 (from 5% to 23%), and patient 7 (from 7% to 63%). There was no mean significant difference between CGM values (5.75 [standard deviation, 2.49] mmol/L) and self-monitoring of blood glucose values (5.76 [standard deviation, 2.32] mmol/L) (P > 0.05). Pearson correlation analysis showed positive correlation between CGM values and self-monitoring of blood glucose values (r = 0.88, P < 0.05). Clarke Error Grid Analysis showed that 91.5% of pairs were located in areas A and B.

CONCLUSIONS

Continuous glucose monitoring is useful for detecting hypoglycemia and evaluating curative effect, but the correction of fingertip blood glucose is necessary when the blood glucose is relatively low.

Insulinoma presenting with postprandial hypoglycemia and a low body mass index: A case report

BACKGROUND

Insulinomas are the most common type of functioning endocrine neoplasms of the pancreas presenting hypoglycemic symptoms. Patients characteristically develop symptoms while fasting, but some patients have reported symptoms only in the postprandial state. Repeated and prolonged hypoglycemic episodes can reduce the awareness of adrenergic symptoms, and patients may have amnesia, which delays diagnosis.

CASE SUMMARY

We describe a case of a 24-year-old underweight patient who showed hypoglycemic symptoms for almost 6 years. Although patients with insulinoma characteristically develop symptoms while fasting, this young man had hypoglycemic symptoms up to one hour postprandially, especially after high-sugar meals and after physical activity. The fasting tests and imaging methods performed at local hospitals were evaluated as negative for abnormal results. However, brown adipose tissue exhibited increased metabolic activity, and some muscle groups had histological changes as indicated by positron emission tomography with 2-deoxy-2-[fluorine-18]fluoro-D-glucose integrated with computed tomography. Glycogen deficiency was also histologically confirmed. The patient’s symptoms progressed over the years and occurred more frequently, i.e., several times a month, and the patient had reduced awareness of adrenergic symptoms. The follow-up fasting test was positive, and the imaging results showed a tumor in the head of the pancreas. The patient underwent laparotomy with enucleation of the insulinoma.

CONCLUSION

Weight gain and fasting hypoglycemia are not necessarily characteristics of insulinoma. In prolonged cases, adrenergic symptoms can be suppressed.

Clinical and genetic analysis in a family with familial renal glucosuria: Identification of an N101K mutation in the sodium-glucose cotransporter 2 encoded by a solute carrier family 5 member 2 gene

We report the identification of a mutation in the solute carrier family 5 member 2 (SLC5A2) gene, which encodes sodium-glucose cotransporter 2, in a family with familial renal glucosuria. The proband was a 26-year-old Japanese man referred to the diabetes division with repeated glucosuria without hyperglycemia. His mother, uncle and grandfather also had a history of glucosuria. A heterozygous missense mutation (c.303T>A:p.N101K) in SLC5A2 was identified in the patient and his mother, but not in 200 chromosomes from 100 healthy and unrelated individuals, or in 3,408 Japanese individuals in the Tohoku Medical Megabank. Furthermore, bioinformatics software predicted that this lesion would be pathogenic. We infer that the mutation led to clinically relevant sodium-glucose cotransporter 2 dysfunction. The patient showed no symptoms of hypoglycemia, but continuous glucose monitoring confirmed asymptomatic hypoglycemia.

Factory-calibrated continuous glucose monitoring and capillary blood glucose monitoring in a case with insulinoma: usefulness and possible pitfall under chronic hyperinsulinemic hypoglycemia

The accuracy of factory-calibrated continuous glucose monitoring (fCGM) within hypoglycemic ranges, especially under the status of chronic hyperinsulinemic hypoglycemia like insulinomas, remains an issue. Even so, fCGM is known to be useful for detecting hypoglycemia unawareness in insulinoma cases. A 25-year-old woman presenting with sudden unconsciousness was diagnosed with insulinoma; fCGM facilitated diagnosis by continuous monitoring for hypoglycemia. Before surgery, she was treated with continuous and frequent bolus infusions of 50% glucose via central venous catheter. To evaluate the accuracy of fCGM values in this case, a comparison between fCGM and capillary blood glucose (CBG) values was also performed. According to the simultaneously measured values, those of fCGM were largely in accordance with those of CBG. Moreover, compared with the previously reported case not having glucose infusions via central venous catheter, both the mean absolute relative differences (MARDs) and the absolute differences (Δ glucose) between fCGM and CBG values were larger in the present case, although no significant differences of MARDs and Δ glucose between the two cases were observed in several different conditions including fasting, post-meal, hypoglycemia, and others. Therefore, we should note possible increased differences between fCGM and CBG values in cases using frequent intravenous glucose infusions as well as case-dependent differing levels of consistency between them.

Insulinoma Case Admitted with Reactive Hypoglycemia Symptoms

AIM

To present an insulinoma case with post-prandial hypoglycemic symptoms associated with glucose inducible endogenous hyperinsulinemia.

CASE

A 52-year-old female patient was evaluated for hypoglycemic symptoms especially those occuring within 3 hours after consuming sugary foods. These symptoms were persistent for a year and a half. She was diagnosed with reactive (post-prandial) syndrome and followed a recommended diet and was given acarbose but there was no improvement. The results suggested post-prandial endogenous hyperinsulinemia related hypoglycemia. Multiphasic computerized tomography revealed an 11x15x12 mm size mass lesion, anteriorly in the head and uncinate process of the pancreas and then the patients were treated surgically with pancreatic enucleation and cured.

CONCLUSION

Distinguishing post-prandial syndrome by careful history and clinical evaluation in patients with postprandial symptoms is of great importance in terms of cost-effectivity. However, it should not be forgotten that although organic pathologies are mostly presented with fasting hypoglycemia, they may also cause post-prandial symptoms. Severity and progression of the symptoms that point to neuroglycopenia is important, and in this condition the most convenient clinical approach to the patient should be performed with careful and appropriate assessment steps.