What is Type 2 Diabetes Mellitus?

(National Diabetes Services Scheme, n.d.)

Type 2 Diabetes Mellitus (T2DM) is a metabolic disorder that occurs when the body either doesn’t produce enough insulin to remove the glucose, or the cells of the target organs are insulin resistant. Diabetics have a large amount of glucose (also known as blood glucose or blood sugar) in their blood. And this can lead to many health complications, if not treated. To fully understand Type 2 diabetes we must first look at the normal function of glucose in our body and the way insulin works to regulate blood glucose levels.

Glucose – Where is it from?

Glucose enters our body from the foods we eat. Carbohydrates, such as bread, fruit, milk, potatoes, and rice are the largest/main source of glucose in a typical person’s diet (Hess-Fischl, 2018). The carbohydrates are broken down by the digestive system, and made into monosaccharides (which are glucose, fructose, and galactose). Then the glucose is transported across the intestinal membrane via the bloodstream to the rest of the body.

The goal of glucose is to get into the target organ cells so that the organs can use them. The body needs the hormone insulin, which is produced by the pancreas, to help transport glucose into the cells and out of the bloodstream. Diabetics have a large amount of glucose in their blood and having a high blood sugar level is very hazardous. Hyperglycaemia, which translates to high (hyper) glucose(gly) in the blood(anemia), is the defining characteristic of diabetes (Hess-Fischl, 2018). This mainly occurs when diabetics are unable to keep their blood glucose levels under control, due in part to the fact that they either don’t produce adequate amounts of insulin or their cells are insulin resistant.

Hyperglycaemia has many signs and symptoms, that act as warnings to indicate to you that your blood glucose levels are high. These symptoms include increased thirst and/or hunger, frequent urination, sugar in the urine, headache, blurred vision and fatigue (Hess-Fischl, 2018). If the blood glucose levels remain high for an extended period, it could lead to serious problems with the eyes(blindness) and heart (heart disease).

If having too much glucose makes us sick, why do we need it?

Glucose is very important for the body. Cells use glucose for energy. Most importantly your brain cells are fuelled by glucose (Mergenthaler et al., 2013).  Without it, you won’t be able to efficiently process information and your body would not adequately work. Once the body uses the energy it needs, there is still some left which gets stored as glycogen in the liver and muscles. This storage of glucose allows for the glycogen to be readily broken down when energy is needed. Glycogen serves as a buffer to maintain blood glucose levels (Berg, et al., 2002). For example, when you suddenly engage in strenuous activity, the glycogen is broken down and the glucose is released from the liver and muscles to fuel the body

Is there a way to stop glucose from causing issues?

The human body has a well-made system that helps regulate the level of glucose in our blood constantly. The pancreas has cells known as Beta(β) cells that monitor your blood glucose levels constantly. After eating, also known as the postprandial period, the volume of glucose in your blood rises and the β-cells release insulin into your bloodstream (MacDonald, Joseph, and Rorsman, 2005). The insulin then encourages the muscle, fat and liver cells to uptake the glucose from the blood. The higher the insulin sensitivity the better the cells respond to insulin.

How does this relate to Type 2 Diabetes Mellitus?

Type 2 diabetes mellitus disrupts this harmonious relationship. The pancreas is not secreting enough insulin, which means the sugar is starting to accumulate in the blood and the person’s blood sugar levels are much higher than normal. Or the pancreas is producing insulin, but the cells have developed a resistance to insulin and ignore the message sent by the released insulin to remove the glucose from the blood.

This resistance to insulin is caused when there is an excess of glucose in the blood, and the cells’ ability to remove the blood glucose reduces. As this is happening, the pancreas begins to work harder and releases more insulin than normal to compensate for the increasing resistance, over time this becomes too much for the pancreas and it is unable to continue maintaining a safe blood sugar level (Harrar, 2019). This leads to the development of type 2 diabetes mellitus.

The excess of glucose in the blood is usually caused by being less active and having an excess of body fat. According to Chatterjee, et al., (2017) there is currently a global rise of obesity and physical inactivity, which has resulted in an increase in the number of patients with type 2 diabetes. T2DM is caused by an unhealthy diet, lack of exercise and obesity. There are many contributing risk factors for type 2 diabetes including being above the age of 40, having a close relative with diabetes, being overweight or obese, or if you are of South Asian, Chinese, African Caribbean or black African origin. (NHS, 2017)

Symptoms and Complications

The main symptoms are:

  1. Frequent urination,
  2. Constant thirst,
  3. More tired than usual
  4. and losing weight without trying to (Diabetes UK, n.d.).

Though diabetes has many symptoms, sometimes they go unrecognized and people unknowingly live with it for up to 10 years before being diagnosed (Diabetes UK, n.d). Having high blood sugar levels for a long period can be seriously damaging and lead to damage to your heart, eyes, feet and your kidneys.


Currently, there is no cure for type 2 diabetes. However, losing weight, eating healthier and exercising, can help manage the disease. When you exercise for a long duration, such as going for a long walk or run, the muscles take glucose more readily than normal, which helps lower your blood sugar levels.

If changing your lifestyle isn’t enough to manage blood sugar levels, you may also need diabetic medication or insulin therapy (, 2019). Most doctors recommended Metformin, which helps lower glucose production in the liver and improves your body’s sensitivity to insulin (, 2019).


Written by Keirra Phillips


Berg, J., Tymoczko, J. & Stryer, L., 2002. Chapter 21, Glycogen Metabolism. In: Biochemistry. 5th edition. New York: W H Freeman.

Chatterjee, S., Khunti, K. & Davies, M. J., 2017. Type 2 diabetes. The Lancet, 389(10085), pp. 2239-2251.

Diabetes UK, n.d. What are the signs and symptoms of diabetes?. [Online]
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Harrar, S. (2019). Insulin Resistance Causes and Symptoms. [Online] EndocrineWeb. Available at: [Accessed 11 Dec. 2019].

Hess-Fischl, A., 2018. Hyperglycemia: When Your Blood Glucose Level Goes Too High. [Online] Available at:
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MacDonald, P., Joseph, J. and Rorsman, P. (2005). Glucose-sensing mechanisms in pancreatic β-cells. Philosophical Transactions of the Royal Society B: Biological Sciences, [Online] 360(1464), pp.2211-2225.                                            Available at: [Accessed 12 Dec. 2019]. (2019). Type 2 diabetes – Diagnosis and treatment – Mayo Clinic. [online] Available at: [Accessed 12 Dec. 2019].

Mergenthaler, P., Lindauer, U., Dienel, G. and Meisel, A. (2013). Sugar for the brain: the role of glucose in physiological and pathological brain function. Trends in Neurosciences, [Online] 36(10), pp.587-597. Available at: [Accessed 11 Dec. 2019].

National Diabetes Services Scheme (n.d.). Type 2 diabetes. [Image] Available at: [Accessed 12 Dec. 2019].

NHS, 2017. Symptoms, Type 2 diabetes. [Online]
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[Accessed December 2019].

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