Type 2 Diabetes Mellitus

Diabetes mellitus is a worldwide public health problem that affects millions of people. There are primarily two types – Type I and Type 2 diabetes mellitus. Epidemiological studies estimate that nearly 3 million people in the United Kingdom and nearly 26 million people in the United States have type 2 diabetes mellitus.1

Here we discuss this clinical condition in a bit more detail.

Why does type 2 diabetes occur?

In type 2 diabetes, patients have abnormally high blood sugar levels that occur due to the body’s inability to produce adequate amounts of insulin. In some cases, while insulin production may be sufficient, the cells do not respond to its actions resulting thus in
high blood sugar levels. This lack of response to insulin is called insulin resistance.

Insulin resistance is a condition where due to lack of response to insulin, glucose does not enter the muscle cells and the liver produces a lot more glucose as well. In the initial stages of insulin resistance, patients develop an excessive production of insulin to try and compensate for the decreased entry of glucose into the cells. However, over time, insulin resistance persists and insulin secretion decreases. A combination of these two is essential to diagnose type 2 diabetes.

Type 2 Diabetes mellitus = Insulin Resistance + Decreased Insulin Production

There are other theories of development of type 2 diabetes which indicate that altered metabolism and high levels of amino acids (protein molecules) can eventually lead to it. A number of genes have also been mapped which indicate the causes for decreased insulin production, but a detailed discussion on this is out of the scope of this article.

Risk factors for type 2 diabetes

There are a number of risk factors that can make patients prone to developing type 2 diabetes –

1. Age more than 40 years

2. Obesity – Body mass index > 30 in Caucasians, > 26 in South Asians.

3. Ethnicity – Commoner in south Asian men

4. Family history of type 2 diabetes

Clinical features

Patients with type 2 diabetes often have 3 main symptoms –

  • Polyuria – This refers to excessive frequency of urination, particularly at night.
  • Polydipsia – This refers to excessive thirst.
  • Polyphagia – Indicates increased food intake.

In addition to these symptoms, patients also complain of weight loss over a period of time. Patients also feel excessively tired as well.

However, most patients with type 2 diabetes do not present with any symptoms, and as a consequence the disease can go unnoticed for a number of years and is diagnosed during routine health checkups.

Some patients who have had undiagnosed diabetes for a number of years can present to their doctor’s with an infection or with blurred vision. Infections are usually fungal infections and usually require treatment. Patients may also complain of constipation and muscle cramps.


The diagnosis of type 2 diabetes is made from blood tests –

1. Fasting blood sugar levels – Levels more than 7 mmol/L indicates type 2 diabetes.

2. Urine tests – Presence of high levels of glucose in the urine indicates type 2 diabetes.

3. Glucose tolerance test – In this test, following estimation of fasting blood glucose levels are measures, patients are administered a glucose load and their blood sugar checked again in 2 hours. The results are expressed as either normal, impaired glucose tolerance or type 2 diabetes.

Below is a table that illustrates this better.






Glucose Tolerance




< 6 mmol/L

> 6.1 –
<7 mmol/L


 2 Hr Post  

< 7.8 mmol/L

>7.8 – <11.1 mmol/L

>11.1 mmol/L


4. HbA1c – Also called glycated haemoglobin, this indicates the binding of glucose to Hemoglobin A. It is a good indicator of control of blood glucose levels over 2 to 3 months, and levels > 6.5% indicate diabetes mellitus.

According to the American Diabetes Association (ADA), a combination of the criteria for diabetes described above (fasting blood glucose, glucose tolerance test and HbA1c) is essential to make a diagnosis of type 2 diabetes.

Treatment of type 2 diabetes

Diabetes requires different modalities of treatments, and it is a combination of these that helps manage patients with type 2 diabetes adequately. Unfortunately there is no cure.

1. Lifestyle modifications – In diabetes, it is essential to reduce total sugar intake in the diet. This means cutting down on sweets, cakes cookies and carbohydrates. Adequate exercise is essential and if obese, losing weight is also extremely important.

2. Medical therapy – This includes treatment with a variety of drugs that help lower blood sugar levels and allow for increased sensitivity to insulin. There are a large variety of drugs that are available to patients, and a detailed discussion on these is out of the scope of this article, but below is a brief discussion on the commonly used ones –

  • Metformin – This is the most commonly used drug that falls under the category of biguanides. It exerts its effects by increasing the sensitivity of the cells to insulin and also reduces the amount of glucose that is released by the liver into the blood. Side effects include metabolic acidosis (rare) and in some cases diarrhoea.
  • Gliclazide – This is a sulphonylurea drug that increases the insulin production and secretion by the pancreas. However, a close eye must be kept on blood sugar levels as they can cause a significant drop in blood sugar levels fast.
  • Pioglitazone – This drug falls under thiozolidinediones and increases the sensitivity of cells to the actions of insulin, thus allowing for glucose to move into the cells. They should be avoided in patients with heart failure.
  • Insulin – This is used in patients who have poor diabetes control despite maximum oral therapy. Patients can be taught to self-administer these drugs at home.


Type 2 diabetes mellitus is a common medical problem that requires lifelong treatment. With simple diagnostic tests available, it can be diagnosed early and treatment started promptly.


U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, 2011. National diabetes fact sheet: national estimates and general information on diabetes and prediabetes in the United States, 2011. Available at http://www.cdc.gov/diabetes/pubs/pdf/ndfs_2011.pdf. Accesses March 24, 2013