What causes diabetes?

What causes diabetes is an extremely common question.  As you know there are many different types of diabetes.  The most commonly known type of diabetes is type 1 diabetes and type 2 diabetes.  Although they both result in high blood sugars, which causes type 1 diabetes versus type 2 diabetes is totally different.  In this blog post, we will review the causes of diabetes in detail.  In a nutshell,  genetic and environmental factors either individually or as a combination of both causes diabetes. If you want to learn about our online diabetes doctors and our telehealth diabetes care center, contact us after you finish reading the article and remember to share with other people who may benefit from the information.

Less well-known types of Diabetes

What causes Type 1 diabetes and LADA?

Autoimmune destruction of beta cells for unknown reasons is the cause of type 1 diabetes.  The distraction starts happening at a very early age.  The process is sometimes very quick and sometimes it takes a while.  When the process is a very quick presentation for type 1 diabetes happens at a very early age such as in the first 5 years of life.  When the process is slow, type 1 diabetes can present at later ages such as between 20 years of age and 40 years of age.  This is sometimes called type 1.5 diabetes (LADA)

What causes diabetes type MODY?

Lastly, there is a totally genetic type of diabetes that has nothing to do with insulin resistance or environmental factors.  This is called MODY (maturity-onset diabetes of young).  This is a totally genetically inherited situation.  Most cases of MODY are mild and do not cause complications of diabetes.  MODY has 6 different types.  The most common types are MODY–2 and MODY–3.

How do you know if you have MODY or not?
  • If you have diabetes diagnosed at a young age such as in the late teenage years but blood sugars are only mild to moderately elevated.
  • You have a strong family history of people in her family with a type of diabetes that does not progress or cause complications (most people in your family either uses no medication or a single oral pill for decades).
  • They think you may have type 1 diabetes because you are young but antibodies such as GAD-65 and IA-2 antibodies are negative in blood testing.

To understand what type of diabetes you have it is extremely important. So please go a specialist evaluation by a diabetes specialist and/or endocrinologist.

What causes type 2 diabetes?

Since type 2 diabetes is the most common type of diabetes we will start with the causes of type 2 diabetes.

Type 2 diabetes is a combination of insulin resistance, reduction in insulin production, elevated blood sugars.

The exact cause of diabetes may be difficult to determine in each individual patient and may be quite different from person to person. So, we will go over what causes diabetes type II one by one. As a result, you will have more knowledge to potentially correct these causes to prevent diabetes.

Most people know at least a little bit about diabetes. You can make an association between insulin resistance, metabolic syndrome, high cholesterol, high blood pressure.  Typically, these disorders are interrelated to each other.  Most of the time, it all boils down to insulin resistance.

Genetic factors play a role.

Do genetic factors cause diabetes?

Genetic factors and environmental factors are the two main contributors that cause diabetes.  When we talk about genetic factors we mean what you inherited from your mother and father which determines your risk of diabetes.  Also, some races are more prone to have diabetes than others. African American, Alaska Native, American Indian, Asian American, Hispanic/Latino, Native Hawaiian, or Pacific Islander are at higher risk genetically.

Beta cells which are insulin-producing cells are genetically programmed to produce only so much insulin. And, this is genetically determined. Just like your height is mostly genetically determined, your insulin production capacity is also genetically determined.  When environmental factors put stress on beta cells to make more and more insulin, at some point beta cells will start failing.  The most important environmental stress is insulin resistance.

Sometimes a single genetic mutation can lead to diabetes independent of and environmental factors. This type of diabetes called maturity-onset diabetes of young (MODY).  Let’s begin to talk about insulin resistance to start with.

Insulin resistance

Can insulin resistance cause diabetes? Absolutely! Insulin resistance as we discussed is the most common environmental trigger to cause type 2 diabetes in the setting of genetic predisposition.

What causes insulin resistance?

While we are discussing what causes diabetes we should look into the root cause of the problem. Although there is a huge genetic component in diabetes, insulin resistance is the most important determining factor among the causes of diabetes.  As insulin resistance gets worse in years it can unmask an underlying insulin production defect.  For example, a patient who inherited diabetes genes from his or her family would never become diabetic if he or she did not develop insulin resistance.

Chemicals/hormones as a cause for insulin resistance and diabetes

Insulin resistance occurs due to certain chemicals/hormones that fat cells secrete in the body. Some of them are known as leptin, interleukin, tumor necrosis factor-alpha.

One important fact is that insulin resistance starts many years before high blood sugar appears.  Initially, mildly high blood sugar develop.  We call this prediabetes.  When blood sugars are very high we call it diabetes.  One of the early signs that your body is trying to keep up with the insulin requirement due to insulin resistance is the increase in the levels of proinsulin.  Proinsulin is the molecule our body produces initially that is later cleaved to turn into insulin.  Elevated proinsulin levels can be a clue towards the development of diabetes in the future.

Lifestyle factors as a cause for diabetes and insulin resistance

The most common risk factors that cause diabetes and insulin resistance is weight gain, obesity, and inactivity.  With excessive weight gain and obesity, the stress develops in fat cells.  That stress causes inflammatory markers to rise such as interleukin, tumor necrosis factor-alpha.  These inflammatory cytokines can be toxic to beta cells (insulin-producing cells).

Cytokines as the cause of insulin resistance and diabetes

The cytokines (a type of hormone that helps in communication between cells) can be released from stressed fat cells(Excessive fat storage in the fat cells create stress). This can also disable the insulin receptors that recognize the insulin in the bloodstream.  When there is a problem in the receptor, the body cannot use insulin appropriately and there will be a need for more insulin in order to stimulate the receptors.  And that is the reason for insulin resistance most of the time.  Due to the inflammatory substances, most patients with obesity feel tired most of the time.  This problem leads to more inactivity.  As a result, obesity and insulin resistance worsen in a vicious cycle.

Fatty acids as a cause for diabetes

When there is too much fat in the fat cells fatty acids also start to escape the fat cells into the bloodstream.  Fatty acids are just like cytokines and disable the function of insulin receptors. Fatty acids also reduce insulin production from beta cells.

Abdominal Obesity

The type of obesity matters

The type of obesity also makes a difference in insulin resistance.  The fat in the abdominal area is more likely to cause insulin resistance and diabetes than the fat in the buttocks and thighs.

Leptin is a hormone that signals the number of fat stores in the body through the hypothalamus.  Leptin deficiency is also a cause for diabetes. Leptin deficiency is very rare and can be a genetic disorder.

Adiponectin is a hormone that reduces insulin resistance.  The deficiency of adiponectin also correlates with insulin resistance and diabetes. Healthy fat cells release adiponectin. As we discussed, excessive fat storage within fat cells will lead to stress. In turn, Adiponectin levels will go down.

How to know if you have insulin resistance? 

If you have we have 1 or more of the factors below you should be evaluated for insulin resistance or diabetes. These factors can cause diabetes and or can be simply associated with insulin resistance that causes diabetes.

  • HDL below 50 mg/dL in women and below 40 mg/dL in men
  • Elevated blood pressure
  • Elevated triglyceride levels about 150
  • Acanthosis nigricans which is darkening of the skin at the back of the neck and under her arms which also has a velvety texture.
  • Body mass index more than 27 for Americans, 23–24 for Asians and Indians.
  • Waist circumference over 40 inches (men) or 35 inches (women)
  • Polycystic ovarian syndrome
  • Gestational diabetes history
  • Delivering a large baby

Is diabetes your destiny?  Can a high or low birthweight be a cause of diabetes?

Definitely.  A lot of studies indicate that low birth weight and high birth weight can factor in insulin resistance and diabetes.  So if you came into this world underweight and later turned out to be overweight your risk of diabetes is very high.  Even the infants with normal weight, if they have slow growth in the first 3 months they have a higher chance of diabetes in the future.

In addition, having a high birth weight can be a cause of diabetes.  Sometimes this is related to high blood sugar during pregnancy which is called gestational diabetes.

Prematurity at birth also can be a cause of diabetes.

What medications cause diabetes?

The short answer is many.

What medications are responsible as a possible cause of diabetes? Although the medications below increase the risk or cause diabetes, benefits to risk ratio are important.  If your doctor prescribed any of these medications for other reasons, ask your physician if there is an alternative.  Do not stop medications you are on due to being afraid of being a diabetic. Consult with your doctor. Not taking these medications may have more severe consequences.

List of medications with increased risk of diabetes or cause diabetes

Steroids, prednisone, can cause diabetes by increasing insulin resistance but also by increasing glucose production from the liver.

Moxifloxacin which is an antibiotic causes diabetes by altering insulin secretion.

Antipsychotic medications such as clozapine, iloperidone, olanzapine, paliperidone, quetiapine, risperidone causes diabetes by increasing insulin resistance.

Beta-blockers commonly used for heart problems such as atenolol, metoprolol, propranolol are also agents that can reduce insulin sensitivity and a potential cause for diabetes.

Niacin (nicotinic acid) increases the glucose release from the liver, statins also increase the risk of diabetes with unknown mechanisms.

Blood pressure medications such as hydrochlorothiazide, chlorthalidone, chlorothiazide, indapamide cause diabetes by decreased insulin secretion and increased insulin resistance.

Combination estrogen-progestin oral contraceptives, progestin-only contraceptives can also increase insulin resistance and cause diabetes.

Immunosuppressive agents used for organ transplants such as cyclosporine (cyclosporin), sirolimus, tacrolimus can cause diabetes by reducing insulin secretion.

Summary

The bottom line…diabetes has multiple causes. I hope we were able to answer your question for “what causes diabetes”  Depending on the type of diabetes such as diabetes type 1, diabetes type 2, diabetes type 1.5 (LADA) or MODY causes for diabetes will differ. Regarding the most common type of diabetes which is type 2 diabetes, the cause of diabetes is a combination of multiple factors such as genetics, as an inheritance from your first-degree relatives but also your race along with many other environmental factors.

Environmental factors are the second most important cause of diabetes.  These environmental factors include obesity, physical inactivity, excessive calorie intake, diet composed of refined sugars and unhealthy fat.  Preventing diabetes is possible.  Since now you know what causes diabetes you can take necessary measures in order to prevent diabetes.  Type 1 diabetes, at least currently, is not preventable. However, it is completely manageable.  With the help of technology and education, patients with type 1 diabetes, today have a totally normal life without complications.

For more information and an appropriate evaluation contact us at www.sugarmds.com.

Author: Ahmet Ergin, MD, FACE, CDCES, ECNU

About the author: Dr. Ergin operates a large diabetes practice mostly in Jupiter, FL yet can see diabetic patients across entire state of florida via a unique telehealth platform which also allows him to track patient progress and be available at all times.