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Obesity: the greatest cause of type 2 diabetes

Jackie Reynolds
Diabetes Specialist Nurse
Cambridge University Hospitals Trust

According to the Department of Health, 2.35 million people in England have type 2 diabetes, and these figures will rise to more than 2.5 million by the year 2010.(1)
There are three main forms of diabetes: type 1, type 2 and gestational diabetes.(2) Around 95% of those with diabetes have type 2, and 80% of these are managed and cared for in primary care.
The onset of type 2 diabetes is often insidious, and the condition can be present for many years before detection. Diabetes UK suggests that 750,000 people in the UK may be unaware that they have this condition.(3)
In 2003, when the National Service Framework for Diabetes published its delivery strategy, as well as the cost of health to the individual, it was estimated that 5% of all NHS costs could be attributed to the burden of diabetes.

What is type 2 diabetes?
Type 2 diabetes occurs when the body becomes resistant to insulin and there is an inadequate supply of insulin to counteract this. It presents more often in:

  • People over 40 (or even younger in people of South East Asian or Afro-Caribbean descent).
  • Overweight or obese individuals, especially with central adiposity.
  • People unable to do or not doing any physical activity.
  • People who have direct family members with type 2 diabetes.

Diabetes significantly increases the risks of cardiovascular disease, blindness, kidney failure and amputation (see Box 1).


Obesity is a major influence in the body's resistance to insulin. The bigger the body mass index and the bigger the waist measurement, the bigger the likelihood of type 2 diabetes onset. Most people who present with type 2 diabetes are either overweight (BMI above 25) or obese (BMI above 30). We are becoming larger: over half the UK population are now collectively classified as either overweight or clinically obese. By the year 2010, it is estimated that 25% of the UK population will be obese. An important study from Finland confirms and extends that sustained changes in lifestyle can substantially reduce the development of type 2 diabetes in middle-aged adults at high risk of diabetes.(4)
The lifestyle interventions include:

  • Better diet.
  • Increased physical activity.
  • Modest weight loss.

After four years, the lifestyle intervention group had more than a 50% reduction in diabetes incidence, although the average weight loss was low, about 3kg or less than 5% of body weight.
 So the simple and rather wonderful answer to the above question is: in the majority of cases, type 2 diabetes is preventable. People can do something to help themselves rather than rely on the pharmaceutical industry, but it needs positive reinforcement and support from healthcare professionals. Increasing physical activity can dramatically reduce the incidence of type 2 diabetes (see Box 2).


However, if a person with diabetes is motivated to lose weight, medication can be used to assist. Sibutramine, orlistat and the new agent, rimonabant, can help, but full assessment needs to be undertaken before a drug is prescribed, and the patient needs to be aware of all possible side-effects.

The following are some guides to help in the diagnosis of type 2 diabetes:5

  • Obtain venous blood sample, preferably a fasting glucose and send to the laboratory.
  • Check for level of ketones in urine, to rule out type 1 diabetes.
  • Asymptomatic? Repeat fasting venous glucose sample on a different day.
  • Do not use HbA1c to make a diagnosis of diabetes.



Treatment options for people with type 2 diabetes include lifestyle changes and referral to a structured education programme to cover how to:

  • Stop smoking.
  • Rebalance energy by:
    • Increasing physical activity.
    • Decreasing amounts of fatty foods and sugar.
    • Increasing fruit, vegetables and wholegrain foods.
  • Taking medication regularly:
    • Lowering glucose levels.
    • Lowering cholesterol.
    • Lowering blood pressure.
  • Monitoring glucose levels:
    • Home blood glucose monitoring.
    •  Regular HbA1c.
  • Having an annual review, including:
    • Retinal screening.
    • Foot examination.
    • Blood pressure monitoring.

Should we screen for diabetes?
The debate about whether or not we should have a national screening programme for diabetes will not be resolved until we get the final results of the major European study ADDITION.(6) This large-population, randomised prospective study will conclude in June 2010, with over 3,000 people currently enrolled from at-risk groups that have not yet been identified with diabetes. They will then be randomised into a control group or an intensive follow-up group to find outcome measures to evaluate health-economic consequences of screening and early intervention in type 2 diabetes. We are hoping that the ADDITION study will prove one way or another that screening is both cost-effective and of benefit to the health of the population as a whole.
The provision of high-quality structured diabetes education is a vital part of any diabetes service. Its importance is set out in the National Service Framework for Diabetes and reinforced by the NICE Health Technology Appraisal, Guidance on the Use of Patient Education Models for Diabetes.(7)
There is a legal obligation upon primary care trusts to have the NICE recommendations implemented by January 2006. There are many structured education models that fulfil the NICE criteria, so check out what is happening in your area for people with type 1 and type 2 diabetes. National programmes for structured group education for people with type 2 diabetes include the Diabetes X-PERT Programme and Diabetes Education and Structured Management for Ongoing and Newly Diagnosed (DESMOND).

The message to all of us is to be more physically active. Even a modest weight loss will dramatically improve our chances of not getting type 2 diabetes. The Department of Health recommends 30 minutes of aerobic exercise five times a week. To reduce the burden of diabetes, support from policymakers and the healthcare system is needed to accomplish these important goals. Now, will you please excuse me, I am just off to walk the dog - briskly!


  1. DH. Diabetes. Available from:
  2. WHO. Diabetes melitus.Available from:
  3. Diabetes UK. Introduction to diabetes. Available from:
  4. Tuomilehto J, et al. Prevention of type 2 diabetes mellitus by changes in lifestyle among subjects with impaired glucose tolerance. N Engl J Med 2001;344:1343-50.
  6. US National Institutes of Health. The ADDITION Study. Intensive treatment and complication prevention in screen detected type 2 diabetes. Available from:
  7. NICE. Diabetes (type 1 and 2) - patient education models. Available from: