Type-2 diabetes mellitus is caused either due to insufficient amounts of insulin or when insulin that is released, is ineffective in controlling blood glucose levels. Pancreas, an organ located below and behind the stomach produces a hormone insulin ( released from the beta cells of islets of langerhans in pancreas).
This hormone is released by the pancreas when we eat. Food that is broken down in the stomach is released as glucose into the bloodstream. This increases the blood glucose levels and triggers pancreas to produce insulin which then travels through the bloodstream to bind with the insulin receptors on the cells. Insulin acts like a key to unlock the doors of cells so that glucose can enter the cells from the bloodstream.
This is how our body maintains the blood glucose levels under normal circumstances. But once diabetes develops, this mechanism gets impaired and the pancreas can no longer produce enough insulin to help glucose enter the body cells or the insulin that is released loses its functional capacity to assist glucose to enter the cells. In this case, pancreas maybe producing normal or higher than normal amounts of insulin in the body to compensate for the inefficacy of insulin, but the glucose levels in the blood remain high inspite of this and leads to Type-2 diabetes.
Type -2 Diabetes Mellitus is Caused by Various Reasons Such As
Family history or ethnic background
Lack of exercise or physical activity
Faulty dietary practices
Family History or Genetics
Type -2 diabetes mellitus is a chronic metabolic condition which is usually caused by genetic factors. Our genes play an important role in causing type -2 diabetes. Thats why some people get type-2 diabetes while others do not. Several genes located on different chromosomes are responsible for causing type-2 diabetes and this is further complicated by the fact that an interaction between these genes and environmental factors triggers diabetes in susceptible individuals.
It has been observed that Asian Indians are more susceptible to type -2 diabetes mellitus as Indians have the genes which cause insulin resistance in the body. Another striking observation is that Indians have a tendency to accumulate fat especially around the waist or abdominal fat which also increases the risk for insulin resistance and thereby predisposes them to diabetes mellitus.
Indians have a higher percentage of body fat as compared to other ethnic groups like caucasians and have a tendency for abnormal distribution of body fat which usually shows as a higher waist to hip ratio. Thats why diabetes mellitus tends to run in families and an individual who has a first degree relative with type-2 diabetes, is more likely to develop this disorder.
Overweight and Obesity
Obesity/overweight: excess of fat in the body is known to cause insulin resistance which may in turn lead to type-2 diabetes. Too much fat in the fat cells or adipocytes is known to affect the sensitivity of insulin receptors present on the cells which may reduce insulin binding and thus cause insulin resistance.
Insulin resistance may then cause high blood glucose levels which may in turn stimulate increased production of insulin by the pancreas leading to hyperinsulinemia. Gradually with the passage of time, pancreas’ continued efforts to release more insulin to make up for the reduced efficacy of insulin eventually leads to beta cell exhaustion.
Once the pancreatic cells ( beta cells in pancreas produce insulin) get damaged, they cannot produce sufficient insulin to maintain blood glucose levels and this leads to type-2 diabetes. This is the reason why obese and overweight individuals are more prone to type-2 diabetes as compared to lean people.
Lack of Physical Activity
Lack of activity or a sedentary lifestyle is mainly responsible for type -2 diabetes in people today. With an increasing trend towards mechanization, people are becoming more dependant on machines for getting their work done as compared to earlier times when most of the jobs were done manually.
Due to this, individuals are gaining weight and excess of body fat leads to diabetes mellitus as discussed earlier.
Faulty Dietary Habits
With a rapid transition in the food habits of individuals, people now depend more on fast food and junk food (which is characteristic of a low fibre, low vitamin and mineral and high fat and cholesterol diet) to fill up their stomachs. Also an irregular eating pattern where binge eating and skipping of meals is very common, is paving the path towards type-2 diabetes mellitus.
With an advancing age, people develop age-related type-2 diabetes due to a decline in organ functioning.