Neuroendocrine tumours (NETs) arise from neuroendocrine cells, which have the unique ability to produce and secrete hormones. These tumours can develop in various parts of the body, including the pancreas, gastrointestinal tract, and lungs.
Due to their ability to secrete hormones, NETs can significantly impact the body’s metabolism, including the regulation of blood sugar levels.
Neuroendocrine Cancer Australia (NECA), is dedicated to assisting individuals with neuroendocrine cancer and their families. NECA offers a wealth of resources, educational programs, and advocacy efforts aimed at deepening the understanding of NETs, improving patient care, and encouraging research advancements. Patients diagnosed with NETs can engage with NECA’s comprehensive support and information by calling the NET nurse line.
Hormonal activity and metabolism
The hormones produced by NETs can have profound effects on the body’s metabolic processes, particularly blood glucose regulation.
Hormones like insulin, glucagon, and other peptides play crucial roles in maintaining normal blood glucose levels.
When NETs secrete these hormones in excess or when their production is dysregulated, it can lead to significant imbalances in blood glucose levels, contributing to:
- Hypoglycemia (low blood glucose level): A condition where blood glucose levels drop below the normal range.
- Hyperglycemia (high blood glucose level): A condition where blood glucose levels rise above the normal range.
We’ll investigate these impacts a bit further down under symptoms.
Causes of blood sugar imbalances for NET patients
There are several causes of blood glucose imbalances in NET patients depending on the kind of tumour.
Insulinomas and hypoglycemia
Insulinomas are a type of NET that originates from the insulin-producing cells of the pancreas. These tumours secrete excess insulin, which can cause blood glucose levels to drop dangerously low, leading to hypoglycemia.
Although insulinomas are relatively rare, accounting for about 4% of all NETs, their impact on blood glucose regulation can be profound and requires careful management.
Glucagonomas and hyperglycemia
Glucagonomas are another type of NET that affects blood sugar levels, but in the opposite direction. These tumours arise from the cells that produce glucagon, a hormone that raises blood glucose levels by stimulating the liver to release stored glucose into the bloodstream.
Glucagonomas are even more rare than insulinomas, making up less than 1% of NETs. However, they can significantly impact a patient’s quality of life by causing diabetes-like symptoms.
Effects of other hormone-secreting tumours
Other NETs, such as somatostatinomas or gastrinomas, can also influence blood sugar levels indirectly.
For instance, somatostatinomas can inhibit the secretion of insulin, leading to hyperglycemia.
Impact of tumour treatment on blood glucose levels
The treatment of NETs can also have significant effects on blood glucose levels. Surgical removal of the tumour, for instance, can lead to fluctuations in hormone levels, potentially causing hypoglycemia or hyperglycemia as the body adjusts.
When a patient undergoes a pancreatectomy, depending on how much of the pancreas is removed it can result in minimal to no beta cells (insulin) or alpha cells (glucagon) left. This means the person needs to be treated with insulin for the rest of their life.
This is further complicated when the person experiences a hypoglycaemia episode, their pancreas cannot produce glucagon to resolve, increasing their risk for severe hypoglycaemia.
Additionally, treatments like chemotherapy, targeted therapy, or peptide receptor radionuclide therapy (PRRT) can impact the pancreas and other organs involved in glucose regulation, leading to further challenges in managing blood glucose levels.
Common blood glucose-related symptoms
NET patients should keep an eye out for a range of blood glucose related symptoms.
Hypoglycemia
Hypoglycemia is a common and potentially dangerous condition for NET patients, particularly those with insulinomas.
Symptoms of hypoglycemia include:
- Sweating
- Dizziness
- Confusion
- Shakiness
And if untreated:
- Seizures
- Loss of consciousness
- Coma
Patients with NETs that cause hypoglycemia must be vigilant in monitoring their blood glucose levels and managing their symptoms promptly.
Hyperglycemia
Hyperglycemia, on the other hand, is typically seen in patients with glucagonomas or other NETs that disrupt normal insulin function.
Common symptoms include:
- Excessive thirst
- Frequent urination
- Fatigue
- Blurred vision
- Unexplained weight loss
Persistent hyperglycemia can lead to long-term complications such as diabetic peripheral neuropathy, kidney damage, and cardiovascular disease, making it crucial for NET patients to manage their blood glucose levels effectively.
Blood glucose fluctuations
NET patients may also experience episodes of blood glucose fluctuations, where they swing between hypoglycemia and hyperglycemia.
These fluctuations can be particularly challenging to manage, as they require constant monitoring and adjustment of treatment plans.
Long-term Complications
Long-term complications of blood glucose imbalances in NET patients can be severe.
Chronic hyperglycemia can lead to:
- Permanent neurological damage
- Cardiovascular disease
- Kidney failure
- Vision problems
- Stress
- Anxiety
- Depression
Diagnosis and monitoring
One or several of these symptoms and conditions described above can be an indication of blood glucose levels being affected by NETs. Diagnosis and monitoring gives patients the best possible chance at managing the disease.
Here’s are some steps a patient might follow below:
1. Blood glucose testing (glucose levels, HbA1c)
Regular blood glucose testing is essential for diagnosing and monitoring blood glucose imbalances in NET patients. This includes measuring fasting glucose levels and HbA1c, a marker that reflects average blood glucose levels over the past three months.
For patients with insulinomas, frequent blood glucose testing is crucial to detect hypoglycemia early and prevent severe episodes.
2. Continuous Glucose Monitoring (CGM)
Continuous Glucose Monitoring (CGM) is an advanced method that allows for real-time tracking of blood sugar levels. CGM devices are particularly useful for NET patients who experience frequent or unpredictable blood sugar fluctuations.
These devices provide continuous data, helping patients and their healthcare providers make informed decisions about diet, medication, and lifestyle adjustments.
3. Hormonal assays for insulin and glucagon
Hormonal assays that measure levels of insulin and glucagon can provide valuable insights into the underlying causes of blood glucose imbalances in NET patients.
For instance, elevated insulin levels may indicate an insulinoma, while high glucagon levels could suggest a glucagonoma.
4. Imaging and functional tests
Imaging studies, such as MRI, CT scans, and functional tests like the Octreotide scan, are crucial in diagnosing NETs and assessing their impact on blood glucose regulation.
These tests help identify the location, size, and activity of the tumour, guiding treatment decisions and monitoring the effectiveness of interventions.
Management of blood sugar levels in NET patients
Fortunately, there are ways that NET patients can monitor and manage their blood glucose levels. This management can lead to better ongoing outcomes as the disease is treated.
Medical treatments
Medical management of blood glucose levels in NET patients often involves a combination of medications and hormone therapies tailored to the specific needs of the patient.
- Medications such as diazoxide may be prescribed to manage hypoglycemia in insulinoma patients. For those with hyperglycemia, insulin or oral glucose lowering medication may be necessary to control blood glucose levels.
- Hormone therapy, such as somatostatin analogues, can help regulate the secretion of hormones that affect blood glucose levels, providing better control and reducing symptoms.
- For patients with significant hypoglycemia, glucose tablets or gel, glucagon injections, or even continuous glucose infusion may be required to prevent and treat low blood sugar episodes.
Dietary and lifestyle modifications
Diet and lifestyle play a critical role in managing blood glucose levels in NET patients. Working with a nutritionist or dietitian can help patients develop meal plans that stabilise blood glucose levels and meet their nutritional needs.
- Tailored meal plans that focus on balanced macronutrient intake, regular meals, and avoiding high-glycemic foods can help maintain steady blood glucose levels. Patients may need to avoid fasting or consuming large amounts of carbohydrates.
- Regular physical activity can help regulate blood glucose levels, but NET patients need to approach exercise carefully. Intense or prolonged exercise can lead to hypoglycemia.
Patients should work with their healthcare team to develop a safe diet or exercise routine that supports overall health without compromising blood glucosecontrol.
Surgical interventions
Surgery is often a key treatment for NETs that cause significant blood glucose imbalances.
- Surgical removal of the tumour, particularly in cases of insulinomas or glucagonomas, can potentially cure the condition and normalise blood glucose levels.
- Partial or total pancreatectomy may be necessary to remove the tumour. This type of surgery can have significant implications for blood glucose management.
Impact on quality of life
Like any condition that affects blood glucose levels, NETs can have a significant impact on a patient’s quality of life. Constant monitoring of blood glucose levels can help patients feel relatively normalised as treatment progresses.
Daily management of blood glucose levels
Managing blood glucose levels is a daily challenge for many NET patients, requiring constant vigilance and adjustments to diet, medication, and lifestyle. This ongoing need for monitoring and management can be stressful and time-consuming.
Coping with hypoglycemia and hyperglycemia episodes
Coping with episodes of hypoglycemia and hyperglycemia can be both physically and emotionally taxing. Patients must be prepared to manage symptoms quickly and effectively, which can cause anxiety and fear, particularly if episodes occur frequently or unpredictably.
Emotional and psychological support
The emotional and psychological toll of living with blood glucose imbalances due to NETs cannot be underestimated. Anxiety about managing symptoms, fear of complications, and the stress of ongoing medical care can all contribute to emotional distress.
Further information and support for people diagnosed with NETs is available by calling the NECAÂ NET nurse line.
