Diabetes – The NET Effect


My chest infection is now settled, as too is the excitement and apprehension behind my first ever Ga68 PET – the outcome of that is still a work in progress. Earlier this year, my thyroid ‘lesion’ on watch and wait was given a ‘damping down’ with the prescription of a thyroid hormone supplement but I await a re-ignition of that small bush fire downstream.

Bubbling behind the scenes and clamoring for attention is the spiking of my blood glucose test results and I was very recently declared ‘at risk’ for diabetes One of my followers entitled a post in my group with “The hits keep coming” in reference to encountering yet another problem in the journey with Neuroendocrine Cancer. I now know how she feels, this issue is a bit of a ‘left fielder’. However, having analysed the situation and spoken to several doctors, I can now put pen to paper.

Neuroendocrine Cancer is not a household name (…… I’m working on that) but diabetes certainly is. The World Health Organisation reports that the number of adults living with diabetes has almost quadrupled since 1980 to 422 million adults. In USA, estimates from CDC stated around 10 million people diagnosed with diabetes with a further 84 million in pre-diabetes state (at risk). In UK around 3.7 million people have diabetes with about 4 times that amount ‘at risk’. It’s a growth industry (…….. but so is NETs – in the last 40 years, the incidence of NETs is rising at a faster rate than diabetes, a disease which some writers have described as an epidemic).

With those numbers, it follows that many NET patients will be diabetic before diagnosis, some will succumb to diabetes whether they have NETs or not, and some may have an increased risk of succumbing due to their treatment. Some may even be pushed into diabetes as a direct result of their NET type or treatment. It’s important to understand diabetes in order to understand why certain types of NET and certain treatments could have an involvement.

The Pancreas

For understanding of this article, it’s worth noting the pancreas has two main functions: an exocrine function that helps in digestion and an endocrine function that regulates blood sugar. I have talked about the exocrine function in relationship to Neuroendocrine Cancer at length – check out this article on Pancreatic Enzyme Replacement Therapy. In this article, I now want to cover the issues with the endocrine function and blood sugar. First a short primer on diabetes – it is necessarily brief for the purposes of this article.

 

Diabetes Primer

TypeS OF DIABETES

Type 1 and Type 2 Diabetes are fairly well-known. There’s actually more than two types, but these are the most common. Type 2 is the most prevalent with around 90% of diabetes cases. When you’ve got Type 1 diabetes, you can’t make any insulin at all. If you’ve got Type 2 diabetes, the insulin you make either can’t work effectively, or you can’t produce enough of it. Additional types may come up in the subsequent discussion.

What is the problem?

What all types of diabetes have in common is that they cause people to have too much glucose (sugar) in their blood. But we all need some glucose. It’s what gives us our energy. We get glucose when our bodies break down the carbohydrates that we eat or drink. And that glucose is released into our blood. We also need a hormone called insulin. It’s made by our pancreas, and it’s insulin that allows the glucose in our blood to enter our cells and fuel our bodies.

If you don’t have diabetes, your pancreas senses when glucose has entered your bloodstream and releases the right amount of insulin, so the glucose can get into your cells. But if you have diabetes, this system doesn’t work properly. Diabetes is associated by being overweight but there isn’t a 100% correlation with that. However, when an individual becomes overweight, there is an increase in free fatty acids in the blood stream which may contribute to reduced insulin sensitivity in the tissues, leading to increased glucose levels in blood.

Symptoms and diagnosis of Diabetes

Different people develop different symptoms. In diabetes, because glucose can’t get into your cells, it begins to build up in your blood. And too much glucose in your blood causes a lot of different problems. To begin with it leads to diabetes symptoms, like having to wee a lot (particularly at night), being incredibly thirsty, and feeling very tired. You may also lose weight, get infections like thrush or suffer from blurred vision and slow healing wounds.

I see these symptoms mentioned very frequently and normally people are trying to associate them with NETs and/or the treatment for NETs.

Diabetes diagnosis is normally triggered diagnosed based on blood tests such as fasting Blood Glucose (snapshot) and/or Glycated Hemoglobin (A1C) or HbA1C.

Complications

Over a long period of time, high glucose levels in your blood can seriously damage your heart, your eyes, your feet and your kidneys. These are known as the complications of diabetes.

But with the right treatment and care, people can live a healthy life. And there’s much less risk that someone will experience these complications.

What are the direct connections with Diabetes and NETs?

It’s not surprising that diabetes is mostly associated with Neuroendocrine Tumors of the Pancreas but there are other areas of risk for other types of NETs including to those who are existing diabetics – see below.

Surgery

The main types of surgery for Neuroendocrine Tumors of the Pancreas are Distal Pancreatectomy (tail), Sub-total pancreatectomy (central/tail), Classic Whipple (pancreaticoduodenectomy – head and/or neck of pancreas), Total pancreatectomy (remove the entire pancreas) or an Enucleation (scooping out the tumour with having to remove too much surrounding tissue). From the PERT article link above (exocrine function), you can see why some people need this treatment to offset issues of reduced production of pancreatic enzymes. The same issue can develop with a reduced endocrine function leading to the development of diabetes.

NET Syndromes

The different types of functional pancreatic NETs often called syndromes in their own right due to their secretory role. One might think that Insulinomas are connected to diabetes issues but this hormonal syndrome is actually associated with low blood sugar (hypoglycemia), although low blood sugar can turn out to be a complication of diabetes treatment.

A NET syndrome known as Glucagonoma (a type of functional pancreatic NET) is associated with high blood glucose levels. About 5-10% of pancreatic neuroendocrine tumors are Glucagonomas, tumors that produce an inappropriate abundance of the hormone glucagon. Glucagon balances the effects of insulin by regulating the amount of sugar in your blood. If you have too much glucagon, your cells don’t store sugar and instead sugar stays in your bloodstream. Glucagonoma therefore leads to diabetes-like symptoms (amongst other symptoms). In fact Glucagonoma is sometimes called the 4D syndrome – consists of diabetes, dermatitis, deep venous thrombosis (DVT), and depression.

Another functional pancreatic NET known as Somatostatinoma is prone to developing insulin resistance. Somatostatinomas produce excessive amounts of somatostatin which interferes with the insulin/glucagon function and could therefore lead to diabetes.

Diabetes caused by cancer or cancer treatment

Worth noting that this type of diabetes is sometimes known as ‘Pancreatogenic diabetes’ and this is actually classified by the American Diabetes Association and by the World Health Organization as type 3c diabetes mellitus (T3cDM) and refers to diabetes due to impairment in pancreatic endocrine function due to acute cancer and cancer treatment (and several other conditions). The texts tend to point to cancers (and other conditions) of the pancreas rather than system wide. Prevalence data on T3cDM are scarce because of insufficient research in this area and challenges with accurate diabetes classification in clinical practice. (Authors note: Slightly confusing as many text say that type 3 diabetes is proposed for insulin resistance in the brain (diabetes associated with Alzheimer’s disease).  There’s another term for a complete removal of the entire pancreas – Pancreoprivic Diabetes

Other treatment risks

Somatostatin Analogues (e.g. Octreotide and Lanreotide) are common drugs used to control NET Syndromes and are also said to have an anti-tumor effect. They are known to inhibit several hormones including glucagon and insulin and consequently may interfere with blood glucose levels. The leaflets for both drugs clearly state this side effect with a warning that diabetics who have been prescribed the drug, should inform their doctors so that dosages can be adjusted if necessary. The side effects lists also indicates high and low blood glucose symptoms indicating it can cause both low and high blood glucose (hypoglycemia and hyperglycemia). For those who are pre-diabetic or close to pre-diabetic status, there is a possibility that the drug may push blood tests into diabetic ranges.
Afinitor (Everolimus). The patient information for Afinitor (Everolimus) clearly states Increased blood sugar and fat (cholesterol and triglycerides) levels in blood: Your health care provider should do blood tests to check your fasting blood sugar, cholesterol and triglyceride levels in the blood before you start treatment with AFINITOR and during treatment with AFINITOR”
Sutent (Sunitinib). The patient information for Sutent (Sinitinib) clearly states that low blood sugar (hypoglycemia) is a potential side effect. It also advises that low blood sugar with SUTENT may be worse in patients who have diabetes and take anti-diabetic medicines. Your healthcare provider should check your blood sugar levels regularly during treatment with SUTENT and may need to adjust the dose of your anti-diabetic medicines.

In rare cases, certain NETs may produce too much Adrenocorticotropic hormone (ACTH), a substance that causes the adrenal glands to make too much cortisol and other hormones. This is often associated with Cushing’s syndrome. Cortisol increases our blood pressure and blood glucose levels with can lead to diabetes as a result of untreated Cushing’s syndrome.

Summary

I think it’s sensible for all NET patients, particularly those with involvement as per above and who are showing the signs of hypoglycemia and hyperglycemia, to be checked regularly for blood glucose and if necessary HbA1c. Many patient information leaflets for the common NET treatments also indicate this is necessary. Always tell your prescribing doctors if you are a diabetic or about any history of low or high blood glucose before treatment for NETs.

My brush with Diabetes (as at Nov 2018)

My blood glucose levels started to climb slightly in 2016 but HbA1c remained normal. However, an HbA1c test in early 2018 put me into pre-diabetic range (44 mmoL/moL). I explained some of the above article to my GP who is corresponding with a diabetes expert at secondary care – the expert suggested that I need to be monitored carefully. I have kept my NET team up to date.

At the time of writing, a retest of HbA1c (3 month interval) came back normal (36 mmoL/moL). I’m now attending a Diabetes Prevention Programme as the request of my GP (voluntary attendance). I have yet to see a trend so will continue doing the course which I think is very educational and am pragmatic enough to know that I do not need to lose weight as one of the aims of reducing my blood glucose and HbA1c levels (something emphasised by the above mentioned diabetes specialist.

I even got on my bike to do a little bit more exercise just in case!

At this point, I cannot yet say if this is the beginning of progressive Type II diabetes or if my medication is causing these spikes in my blood glucose and HbA1c. I will keep you posted.

Summary – if you are noticing these symptoms, get your blood sugar checked (with acknowledgement to Dr Pantalone from Cleveland Clinic)

1. You’re making more trips to the bathroom

Having to go to the bathroom more than normal, particularly at night, is a sign that your blood sugar might be out of whack.

Dr. Pantalone says one of his patients came in for a diagnosis after a family member noticed that he was using the bathroom during each commercial break when they watched TV.

2. You’re getting frequent urinary or yeast infections

When your blood sugar is high and your kidneys can’t filter it well enough, sugar ends up in the urine. More sugar in a warm, moist environment can cause urinary tract and yeast infections, especially in women.

3. You’re losing weight without trying

If you have diabetes, your body isn’t able to use glucose (sugar) as effectively for its energy. Instead, your body will start burning fat stores, and you may experience unexpected weight loss.

4. Your vision is getting worse

High sugar levels can distort the lenses in your eyes, worsening your vision. Changes in your eyeglass prescription or vision are sometimes a sign of diabetes.

5. You’re feeling fatigued or exhausted

Several underlying causes of fatigue may relate to diabetes/high sugar levels, including dehydration (from frequent urination, which can disrupt sleep) and kidney damage.

This feeling of exhaustion is often persistent and can interfere with your daily activities, says Dr Pantalone.

6. You’re noticing skin discoloration

Something that Dr. Pantalone often sees in patients before a diabetes diagnosis is dark skin in the neck folds and over the knuckles. Insulin resistance can cause this condition, known as acanthosis nigricans.

 

Thanks for reading

Ronny

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Author: Ronny Allan

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2 thoughts on “Diabetes – The NET Effect”

  1. I’m in a similar situation. I was diagnosed as pre-diabetic about a year and a half after my NETS diagnosis. Because there’s both a family history and the possible connection to Octreotide, I have been very careful with my diet since that time. Thus far, it seems to be working as my blood sugar and A1C levels have remained virtually unchanged, just a bit above normal.

  2. Interesting. I think the carrier of our SDHB mutation was my grandmother who was diabetic. I wondered if her “diabetes” was her manifestation of her Krebs Cycle Mutation. I did ask a round table of NIH experts if diabetics could be related to SDHB mutations and they said “Plausible” . . . Both her children died of paraganglioma tumors.

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