Differences between Type 1, Type 1.5, Type 2, Type 3 DM

Diabetes mellitus is unfortunately becoming a very common disease. There are two well known types of DM: type 1 and type 2. But what are the differences in these and what is this type 1.5 or type 3 being talked about?

Type 1 diabetes used to be known as juvenile diabetes, this was because symptoms started early, usually during childhood.  It is due to the pancreas producing little or no insulin (the hormone that regulates glucose aka sugar in the blood from getting too high or too low). Type 1 usually have to be on insulin for the rest of their lives in order to manage their blood sugars.  This is extremely difficult for these patients suffering from this disease, they are having to constantly be aware of what they are eating, how this may affect their blood sugar, and how to adjust their insulin dose to keep their glucose level in an optimal range. When blood sugar becomes too low, it may lead to insulin shock, which is life threatening.  When blood sugar stays too high over time and is untreated, it can cause ketoacidosis that could lead to nausea, vomiting, SOB, weakness, confusion or a coma. It can also cause a hyperglycemic hyperosmolar state, which can lead to life-threatening dehydration and coma.  Long term untreated high blood glucose can also lead to cardiovascular disease, nerve damage, kidney failure, damage to blood vessels in eye or blindness, and infections. So you can understand, diabetes type 1 is not an easy diagnosis to have to live with. 

Genetics has been known to play a part in Type 1 diabetes, however this is less likely the primary factor as DM1 disease concordance with monozygotic twins is less than 50%.3  Usually the body’s own immune system is actually what destroys the insulin producing cells in the pancreas for type 1 DM. It is an auto-immune disease, which means the body’s immune system starts to mistakenly starts to attack its own body instead of foreign invaders (bacteria, germs, etc).  Viruses have also been linked to development of diabetes type 1. Coxsackie B virus, Rotavirus, Mumps, Cytomegalovirus, and Rubella have all been associated with type 1 diabetes, specifically the enteroviruses3.  While we do not know exactly how these viruses trigger autoimmunity, it is suspected that when viral infections activate a strong immune responses, and if they are specifically triggering the Beta cells of the pancreas (the cells that make insulin) and causing significant inflammation inside the cells, this can be the first step in the dysregulation of the immune system/ autoimmunity induction. 

However, this viral connection to Type 1 DM has been debated extensively. For example- how can we explain that a REDUCED type 1 diabetes indigence is observed in countries of lower socioeconomic status, which has a HIGHER rate of infection? So taking all the current evidence into consideration, it appears that we cannot assess the full capacity that viruses trigger type 1 DM, especially without taking into consideration the previous pre-disposition to (or advancement of) autoimmunity.

Type 2 diabetes is more common than type 1. More than 30 million Americans have diabetes (1 in 10 people) and about 90-95% of them have Type 2 DM6. This disease usually occurs later in life, and is a chronic, slower developing condition in which your body is unable to metabolize sugar like it should. This can be due to your body developing a resistance to insulin, or your body doesn’t produce enough insulin to maintain normal glucose levels. Diabetes type 2 is linked to obesity and our gut microbe (see here- https://www.naturecurefamilyhealth.com/articles/insulin-resistance-and-our-microbiome/ ). Diabetes type 2 can be controlled (and REVERSED) with healthy diet choices, weight loss, exercising, and removing any other obstacles to cure. 

Type 1.5 DM is the lesser known of diabetes types. This is because type 1.5. is a non-official term that is referring to a form of Type 1 DM, also known as Latent Autoimmune Diabetes in Adults (LADA). This is also has a slow onset like type 2. However its is an autoimmune disease, so it often requires insulin therapy at some point in the future like type 1 which also attacks the insulin producing cells. 

Most physicians are educated that Type 1 and Type 1.5 are non-reversible. However, there are studies7 arising that show beta cells being regenerated (therefore reversing diabetes) with a ‘fasting-mimicking diet’ and water fasting.  Granted, these studies are in only mice currently, and we still will have to address the auto-immunity portion of the disease. However, it is uplifting to see there is HOPE.

Lastly: type 3 diabetes. This is a form associated with Alzheimer’s disease and occurs when the neurons (the nerve cells which transmit information throughout the body) in the brain become unable to respond to insulin, which is essential for basic daily tests, memory, learning, etc. So type 3 is a form of diabetes which targets the brain selectively. 

So in conclusion, here is a very quick bullet list for you to reference:

  • Type 1: autoimmune, body attacks its own pancreas, childhood onset
  • Type 1.5: autoimmune, body attacking itself (pancreas), adulthood onset
  • Type 2: poor diet/weight/gut microbiome related, usually reversible
  • Type 3: related to Alzheimer’s, affects the brain only


  1. Type 1 Diabetes. https://www.mayoclinic.org/diseases-conditions/type-1-diabetes/symptoms-causes/syc-20353011
  2. Hyperglycemia in Diabetes. https://www.mayoclinic.org/diseases-conditions/hyperglycemia/symptoms-causes/syc-20373631
  3. Viral Triggers for Type 1 Diabetes, Pros and Cons. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2570378/
  4. Influence of maternal age at delivery and birth order on risk of type 1 diabetes in childhood: prospective population based family study https://www.bmj.com/content/321/7258/420
  5. Type 1.5 Diabetes. https://www.diabetes.co.uk/type15-diabetes.html
  6. Type 2. https://www.cdc.gov/diabetes/basics/type2.html
  7. Fasting-Mimicking Diet Promotes Ngn3-Driven β-Cell Regeneration to Reverse Diabetes https://www.cell.com/cell/fulltext/S0092-8674(17)30130-7
  8. Researchers link Alzheimer’s gene to Type 3 diabetes https://newsnetwork.mayoclinic.org/discussion/researchers-link-alzheimers-gene-to-type-iii-diabetes/
  9. Alzheimer’s Disease Is Type 3 Diabetes–Evidence Reviewed. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769828/

Leave a comment

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: