Type 2 Diabetes – Etiology and the Role of Life Style

Every year, more than more than 240 million people globally are diagnosed with diabetes. Of this group, approximately 90 to 95% have type 2 diabetes mellitus which is now commonly called type 2 diabetes (T2D). Furthermore, it is estimated that by 2025, the number of individuals with diabetes will total some 400 million.[1] These are only estimates and the actual numbers could very well be higher.

What is T2DM?

T2D is considered an acquired disorder. This disease was formerly referred to as adult-onset diabetes. It is currently the most common type of diabetes. Its old name reflected the age group most affected. Today, however, it is increasingly appearing in younger generations. More children and teens are progressively showing signs of developing T2D largely due to growing rates of obesity.

Another name for this type of diabetes is non-insulin dependent diabetes. This describes one basic characteristic of the disease. For some people, the disease does not always require or depend on injections of insulin to help correct the levels of blood sugar. Instead, lifestyle changes make disease management possible.

What characterizes T2D?

There are several medical characteristics related to T2D. The body has decreased sensitivity to insulin in:

  • Liver tissues
  • Muscle tissues
  • Adipose  tissue

The decreased sensitivity is referred to as “insulin resistance.”  There seems to be a genetic factor involved in some cases, but the majority of cases are due to lifestyle. Type 2 diabetes individuals do not have enough insulin production to maintain appropriate blood glucose levels. While this is the most common characteristics of the disease, it’s not the only one.

Who is at Greatest Risk?

Those at a greater risk for developing T2D are influenced by environment, life style and genetics. Research on twins seems to clarify the link between genetics and T2D. Identical twins, for example, have an equal chance of developing T2D if one has it. The same does not hold true for fraternal twins. Moreover, the odds of a child developing the disease have been shown to increase if both parents have T2D. It is hypothesized that there are multiple genes responsible. They act in co-ordination or interact with the various environmental factors to result in T2D.[2]

Besides genetics, other factors may play a role in whether you become a diabetic. If you are born as an unhealthy weight baby or weigh below average, you have a higher risk of becoming a Type 2 diabetic.[3] Yet, lifestyle plays a significant role in determining whether an individual has the potential to become a type 2 diabetic.  Lifestyle factors include such things as weight, diet and activities. To put it succinctly – if you are sedentary and live on a diet consisting of food of questionable nutrition, you are more at risk of developing T2D than someone who is active and eats healthily.

What is the Etiology of T2DM?

The exact causes of type 2 diabetes are still not clear. It is known that it occurs when the body’s cells become resistant to insulin (hyperinsulinemia). As a result, the pancreas works harder to produce more insulin as an attempt to compensate. Over time, the pancreatic system becomes exhausted.

Most diseases do not have one causal factor. Instead, they are the result of several different factors, and that is true for diabetes. These include:

  • Age
  • Ethnicity
  • Genetics
  • Lifestyle

In the case of T2D, the factor believed to be the major cause of increasing rates of diabetes is not the result of genetic factors but due to an increase in the rates of obesity.[5]

T2DM, Weight, Diet and other Life Style Issues

There is a definite but undefined link between obesity and T2D. It is believed that obesity increases the resistance to insulin. The relationship is not simple, complicated by the fact that not all obese people develop diabetes. However, roughly 80% of diabetic patients are obese. In fact, the increase in the number of individuals who are overweight or obese is said to correlate to the increased incidence of T2D.

Obesity is usually the result of lifestyle choices. T2D is also considered to be related to the individual’s lifestyle. While genetics may provide some clues and influence, it is the environment, particularly the lifestyle choices that affect a predisposition towards becoming a type 2 diabetic. In fact, changing lifestyles throughout the world have resulted in formerly unaffected countries such as China and Japan having higher rates of T2D. The growing availability of affordable Western-style food and the rush for consumerism allies with a less active life. As a result, many members of the middle class are becoming diabetic.

When a diet poor in nutrition is combined with a lack of activity, this may further contribute to the risk of an individual becoming T2D. The more active you are, the less fat is stored. When obesity combines with a sedentary life style, slowly but surely the beta cells residing on the Islets of Langerhan on the pancreas begin to falter in their ability to keep up with the ongoing demand for insulin. As a result, the blood glucose levels rise leading to the eventual diagnose of diabetes.


While doctors and other medical professionals work hard to help prevent prediabetics from becoming diabetic, and teachers and nutritionists stress the need for a healthy diet and exercise, the diabetic epidemic is continuing. With T2D comes more than a single chronic disease. It plays host to various other potentially deadly problems. Among them are coronary heart disease, stroke, nephropathy, peripheral vascular disease, neuropathy, and retinopathy.[8]

If you have weight issues and suspect you may be a candidate for T2D, do not hesitate to talk to your doctor. You can make lifestyle changes and prevent the onset before it is too late.


[1] Warshaw, HS; and Pape, J (2009). Real-Life Guide To Diabetes. Alexandria, VA: ADA.

[2] Guthrie, DW; and Guthrie, RA (2003). The Diabetes Source Book. New York: McGraw Hill.

[3] Meltzer, SJ; and Belton, AB (2009). Diabetes in Adults. Toronto: Key Porter Books.

[4] Jannetta, PJ; Fletcher, LH; Grondziowski,PM; Casey, KF; and Sekula Jr, RF (2010). “Type 2 Diabetes Mellitus: A Central Nervous System Etiology.” Surgical Neurology International, 1(1):31.

[5] Permutt, AM; Wasson, J; and Cox, N (2005). “Genetic Epidemiology of Diabetes” J Clinical Investigation, 115(6):1431-1439.

[6] Marcovitch, H (2006). Black’s Medical Dictionary 41st edition. Lantham, Maryland: Scarecrow Press.

[7] Golay, A; and Ybarra, J (2005). “Link between Obesity and Type 2 Diabetes.” Best Practice & Research Clinical Endocrinology & Metabolism, 19 (4): 649-663.

[8] Pouwer, F; Kupper, N; and Adriaanse, MC (2010). “Does Emotional Stress cause Type 2 Diabetes Mellitus? A Review from European Depression Diabetes (EDID) Research Consortium.” Discovery Medicine, 9(45):112-8.

This article was originally published July 12, 2012 and last revision and update of it was 9/10/2015.