Updated January 2026
Originally published September 2018.
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 clamouring for attention is the spiking of my blood glucose test results and I was very recently declared ‘at risk’ for diabetes with a score just inside pre-diabetes level. Just be aware that my GP wrote a letter to a diabetes expert in my local hospital about my situation i.e. I take a cancer drug which messes with my insulin/glucagon levels. The local expert suggested to proceed with care in my situation. I was fit, not overweight
Diabetes epidemiology
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). Around 415 million people worldwide have diabetes, while 100 million people have cancer. They are unequivocally two of today’s greatest global health challenges. If you have type 2 diabetes, you have a 20 – 30 percent increased risk of developing certain cancers including bowel, liver and pancreatic cancer (not yet known if NETs are included in this anatomical statement). The potential mechanisms underlying this increased risk are complex and incorporate lifestyle, diet, and other known risk factors such as obesity. That said, the risks for diabetes in NETs is a particularly well known phenomenon because
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.
What are the direct connections between Diabetes and NETs?
It’s not surprising that diabetes is mostly associated with Neuroendocrine Tumours 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 Tumours 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 (hypoglycaemia), 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 tumours are Glucagonomas, tumours 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. There’s another term for a complete removal of the entire pancreas – Pancreoprivic Diabetes.
Physical loss or damage to the pancreas (surgery, tumour infiltration, pancreatitis), leading to loss of insulin, glucagon, and digestive enzymes. Key distinction: Type 3c is not autoimmune and not driven by insulin resistance — it’s caused by structural damage to the pancreas. So it is different from Types 1 and 2, although the treatment might be similar.
Other treatment risks
Somatostatin Analogues (e.g. Octreotide and Lanreotide) are common drugs used to control some of the NET Syndromes and are also said to have a mild anti-tumour 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 list also indicates high and low blood glucose symptoms indicating it can cause both low and high blood glucose (hypoglycaemia and hyperglycaemia). 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. However, this may not be regular “type 2” diabetes based on insulin resistance which is the primary underlying problem in type 2 diabetes. So working out whether this is just you being “pushed into diabetic range” because you were on the edge; vs this would not have happened but for the use of SSAs. This can be quite difficult to work out but
There are a lot of myths surrounding this link with somatostatin analogues. Mainly related to claims that everyone gets diabetes when prescribed. This is simply not true.
However, it is a known side effect of lanreotide and other somatostatin analogues, which can interfere with the body’s natural regulation of blood glucose. Based on clinical trials, the incidence of hyperglycaemia (elevated blood sugar) in patients taking lanreotide is around 14%. The mechanism for elevated blood sugar is based on the drugs ability to cause blood glucose levels to either increase or decrease, depending on the patient’s individual hormonal responses as follows:
- Inhibition of both insulin and glucagon: As a somatostatin analogue, lanreotide inhibits the secretion of several hormones, including insulin and glucagon from the pancreas.
- Dominant effect on insulin: Insulin and glucagon have opposing effects on blood sugar. In a healthy state, insulin is the dominant hormone responsible for glucose regulation. Lanreotide’s reduction of insulin often has a greater impact than its reduction of glucagon, which can lead to higher blood sugar levels.
- Varies by condition: While hyperglycaemia is more commonly seen, lanreotide can also cause hypoglycaemia (low blood sugar), particularly in patients with an insulinoma. The effect of lanreotide on blood glucose can vary depending on the patient’s underlying condition, such as acromegaly or neuroendocrine tumors.
So any prescription of Lanreotide or Octreotide, considerations for patients but be made e.g.
- Monitoring is crucial: Patients taking lanreotide should monitor their blood glucose levels regularly, especially when starting treatment or adjusting doses.
- Prior diabetes is a risk factor: The risk of elevated blood sugar is higher in patients with pre-existing diabetes.
- Possible temporary effect: For some people, the hyperglycaemia may be temporary as the body adjusts to the medication. In other cases, as with a severe case report involving a single dose, the effect may be more prolonged.
- Management strategies for existing diabetics: Healthcare providers may need to adjust diabetes medication, possibly by using oral agents like metformin or insulin, and may also recommend dietary changes to help manage glucose levels.
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 (hypoglycaemia) 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 hypoglycaemia and hyperglycaemia, 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 2019)
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 responded suggesting that I need to be monitored carefully as being treated/handled as a regular type 2 diagnosis is not necessarily the best response. He added that HbA1c is not necessarily the best judge in situations where it is thought the diabetes in in relation to pancreatic insufficiency. He also admitted that it is difficult to be clear whether this change is related to my somatostatin analogue (lanreotide) but if is related to pancreatic insufficiency then the worry would be that this would be progressive and this picture would more likely mimic type 1. I put mimic in bold because he was not suggesting this causes Type 1 but only mimicking it – I guess he meant that it can resemble Type 1 in one specific way …..there isn’t enough insulin at the right time.
I kept my NET team up to date. At the time of updating, two separate and sequential HbA1c tests (3-month interval) came back normal at 36 mmoL/moL. I’m 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). My Nov 2019 surveillance tests indicate 39 mmoL/moL so still in normal range. The 44 score above was a spike. Edit: 2026, numerous HbA1c tests later – still in normal range.
I even got on my bike to do a little bit more exercise just in case!
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, for example, see Type 3 above.
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 with 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 bloodstream which may contribute to reduced insulin sensitivity in the tissues, leading to increased glucose levels in the 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 Haemoglobin (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.
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.
Disclaimer
I am not a doctor or any form of medical professional, practitioner or counsellor. None of the information on my website, or linked to my website(s), or conveyed by me on any social media or presentation, should be interpreted as medical advice given or advised by me.
Neither should any post or comment made by a follower or member of my private group be assumed to be medical advice, even if that person is a healthcare professional.
Please also note that mention of a clinical service, trial/study or therapy does not constitute an endorsement of that service, trial/study or therapy by Ronny Allan, the information is provided for education and awareness purposes and/or related to Ronny Allan’s own patient experience. This element of the disclaimer includes any complementary medicine, non-prescription over the counter drugs and supplements such as vitamins and minerals.
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Thank you for this article. I was diabetic before my NET diagnosis in April 2014. Now on lanreotide for several years my blood sugar continues to be an issue. 8 months ago I had to go on insulin as medication wasn’t doing enough. I now see an endocrinologist periodically, sometimes more often, and take blood sugar readings several times a day. HbA1c now hovers at twice normal. I’ve seen my blood sugar be 140s middle of the night and near 200 upon awakening in the morning. I understand the liver dumps glycogen over night.
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.
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.