Types of diabetes
You may have seen the recent national newspaper articles saying there are now 5 types of diabetes. No wonder people get confused but actually in this case there is something to it.
All people with diabetes have problems controlling their blood glucose levels. This is as a result of an impairment in one way or another to the hormone called insulin. The pancreas releases insulin and insulin is the hormone responsible for controlling the body’s glucose levels. With an impaired insulin pathway the body is unable to move glucose out of the blood leading to high blood glucose levels.
There are in fact more than 5 types of diabetes. Most people are familiar with the two most common types – type 1 and type 2 – so what are the other types?
To clear this up, let me explain the different types and how we define them.
Type 1 diabetes is an auto immune disease. It most commonly presents in childhood but can also manifest at any age. In type 1 diabetes the immune system destroys the insulin producing beta cells in the pancreas. This prevents sufferers from being able to produce their own insulin. They therefore cannot control their blood glucose levels. Untreated, this condition is fatal.
Those people with type 1 diabetes will need to inject insulin several times a day for the rest of their life.
90% of people with type 2 diabetes are overweight or obese. The remaining 10% will unlikely develop the condition until well into old age.
Too much fat in the liver, pancreas and the cells of the body prevent insulin working as it should (known as insulin resistance). The pancreas overworks itself trying to compensate for the impaired insulin action and over time can wear itself out. As a result, type 2 diabetes can have varying degrees of severity and treatment.
There are many treatments for type 2 diabetes including oral tablets, injectables and insulin. The most effective remedy in type 2 diabetes however is weight loss and lifestyle changes.
Type 3 diabetes
Injury to the pancreas is one cause of type 3 diabetes. Conditions like pancreatitis or cancer of the pancreas can prevent the pancreas working properly. As a result, blood glucose levels may start to increase resulting in diabetes. To correct the issue, surgery may be needed to remove the effected part of the pancreas. This will lead to lifelong diabetes if the insulin producing part of the pancreas is removed. In such situations the patient will require insulin for the rest of their life.
Cystic fibrosis is another form of type 3 diabetes. It is a genetic condition you are born with and effects the lungs, digestive system and other organs. A sticky mucus covers the effected areas harming function. Insulin is therefore unable to exit the pancreas to control glucose levels in the body. It is a complex condition and more information from the cystic fibrosis trust can be found here.
Maturity onset of diabetes in the young (MODY)
MODY is quite an uncommon form of diabetes but we do see it in practice. 0.5-1% of all patients with diabetes will suffer with MODY.
This is a genetic problem with the insulin releasing beta cells of the pancreas causing diabetes. The usual onset is in people under 45 years old and frequently under 25 years old. These patients have a strong family history of diabetes. Historically patients suffering with MODY were labelled as type 1 or type 2 diabetics. They would also usually find themselves taking insulin soon after diagnosis.
There are four main types of MODY.
HNF1A – MODY
This is a genetic defect that hinders insulin production. These patients are very sensitive to sulfonlyureas (glizlazide, glimepiride, glipizide, tolbutamide, giblenclamide) and often these patients can come off insulin if diagnosed correctly.
HNF4A – MODY
This is similar to HNF1A and these patients are also very sensitive to sulfonylureas.
Glucokinase (GCK) – MODY
Think of GCK -MODY like you would a thermostat. Most people have a glucose setting of between 4-7mmol/l before and 2 hours after meals. GCK sufferers have the thermostat set higher and often have glucose levels running 5.5-8mmol/l. These patients can be managed with only diet. They will run slighter higher with their glucose levels for their entire life but unless developing other forms of diabetes they will not need treatment.
Also known as renal cysts and diabetes. Like the two above HNF disorders these patients do not produce insulin as effectively as someone without the disorder. HNF1B -MODY mutations also frequently exists alongside developing renal cysts.
If you were diagnosed with type 2 diabetes at a young age despite having any of the following:
- were a normal body weight,
- have a strong family history of diabetes
- were prescribed insulin shortly after diagnosis
I would encourage you to speak with your GP about seeing a genetic diabetes specialist.
Medically induced diabetes
There are various different medications which can trigger high glucose levels. To name all of them is beyond the scope of this article so we will focus on the most common in practice. Steroids are a common cause of high glucose levels and I see this commonly in practice.
Steroids can also exacerbate pre-existing diabetes and push glucose levels higher than usual for that patient. Often during steroid treatment patients will require insulin to help manage their glucose levels.
Other medical conditions or treatments which can induce or excacerbate diabetes included thyroid hormone treatment, antipsychotics, antibiotics, antivirals amongst others.
Pregnancy leads to an increased state of insulin resistance due to increased levels of growth hormone, progesterone, placental lactogen and cortisol. As a result, glucose levels can remain elevated throughout pregnancy but usually return to normal upon birth.
Developing gestational diabetes increases your risk of developing type 2 diabetes by 50% over the next 5-10 years. We therefore encourage women to make or stick with significant lifestyle changes if there is scope to do this.
Blood glucose control in gestational diabetes is strict to reduce risks to the baby.
Other forms of diabetes
There are also multiple genetic and endocrinopathy forms of diabetes. Examples include Cushings syndrome (JFK had this), Wolfram syndrome, Acromegaly, Huntingtons chorea, Mitochondrial diabetes, Turners syndrome, Prader -Willis syndrome, Rabson – Mendenhall syndrome and the list goes on. These forms of diabetes are quite rare and will likely the be a side effect of the primary disease.
There are also other forms in children such as neonatal diabetes. Again the scope of this article is for adult forms only.
As you can see, 5 types of diabetes actually does not cover the entire spectrum of diabetes. There are in fact many more types of diabetes than 5. Normally my job involves helping people with type 1, type 2, type 3, gestational or MODY.
The other forms of diabetes are rare and usually dealt with by a specialist in that field.