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Diabetes and obesity: a growing concern

Norma McGough
BSc SRD
Freelance Nutrition Consultant - Diabetes
E:norma.mcgough@diabetes.org.uk

Diabetes mellitus occurs when blood glucose levels are too high because the body cannot use it properly. Insulin, a hormone produced by the pancreas, helps glucose enter the cells where it is used as fuel by the body. Symptoms of untreated diabetes include increased thirst, passing large amounts of urine, extreme tiredness, weight loss, genital itching and blurred vision. The main aim of treatment is to achieve near normal blood glucose levels, which, together with a healthy lifestyle, will improve wellbeing and protect against long-term damage to the eyes, kidneys, nerves, heart and major arteries. The following illustrates the scale of the problem in the UK:

  • Around 3% of the UK's adult population have diabetes.
  • More than 80% of people with noninsulin-dependent diabetes are overweight at diagnosis.
  • People who are overweight are more likely to develop diabetes.
  • Heart disease kills up to 75% of people with type 2 diabetes.
  • Diabetes consumes between 5% and 10% of total healthcare resources (£2.2 billion in 1997), with the majority being spent on complications.

Type 1 diabetes develops when there is a severe lack of insulin because most or all of the cells which make insulin have been destroyed. This type usually appears before the age of 40. Its cause is unknown, although viruses may play a part. It is treated by insulin injections and diet.
Type 2 diabetes develops when the body can still make insulin, just not enough, or when the insulin that the body does make is not used properly. This type usually appears in people over the age of 40. It is common among the elderly and overweight people. It is treated by diet alone, diet and tablets, or sometimes by diet and insulin injections. Approximately 75-90% of people with diabetes have this type.
 
Prevention of type 2 diabetes
Weight management and physical activity are crucial in the prevention of type 2 diabetes. Results from various studies provide us with evidence of significant reductions in the onset of type 2 diabetes when there is intervention with weight management and exercise programmes in people at risk.(3,4)

How does weight loss help?
Obesity is a leading cause of insulin resistance. All aspects of diabetes management are improved by weight ­management. It also reduces the risk of heart disease and stroke, lowers blood pressure, improves mobility, and reduces tiredness and joint damage.
People with diabetes who are overweight or obese have a wide range of symptoms and complications. In general, more symptoms can be related to BMI (body mass index) than can be related to blood glucose. Weight management is associated with a reduction in secondary heart disease and increased life expectancy. Modest weight loss (5-10%) is associated with increased survival in people with type 2 diabetes who are overweight. A weight loss of 10kg leads to a reduction of risk from diabetes-related death by more than 30%.(5)
The United Kingdom Prospective Diabetes Study (UKPDS)(6) showed that to achieve normal blood glucose levels a person with diabetes needs to lose a significant amount of weight (one-third of body weight loss is needed for an average 60kg adult with fasting plasma glucose levels of 12mmol/l to come down to 6mmol/l).
The study also showed that when diabetes is diagnosed, initial dietary advice has a major impact on weight management and blood glucose control. It is important that people with diabetes have a dietary assessment and are given dietary education. The Clinical Standards Advisory Group  recommends that all newly diagnosed patients should have a dietetic consultation within four weeks of diagnosis and that noncrisis dietetic review should be available annually to all people with diabetes.(7)
Dietary intervention for people with diabetes who are also overweight needs to be consistent. Realistic calorie deficits of 500kcal/day usually produce better end results than very restrictive diets.(8) Multiple clinical benefits result from modest weight loss (5-10% weight) that is maintained, ­including improvements in blood pressure management, serum lipids and life expectancy. For each kilogram of weight lost, 12 months after diagnosis, there is an associated three- to four-month increased survival in people with type 2 diabetes who are overweight.(5)
 
Reducing calorie intake
Small changes can have a significant impact on reducing calorie intake if sustained in the long term (see Table 1). Advice needs to be geared to the individual, along with advice on increasing level of activity. The main difference when giving advice to people with diabetes who are also trying to lose weight is that you have to advise individuals on managing blood glucose levels as well as cutting down on calories.

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Very low calorie diets
The use of very low calorie diets (VLCDs) in people with diabetes has been shown to have positive effects on plasma lipids, lowering triglyceride levels and ­raising HDL cholesterol. Most of the benefits relate to energy restriction, not weight loss. Although more weight is lost over a three- to six-month period than using conventional diets, there is no evidence that in the long term (one to two years) the continued benefit of using VLCDs is maintained. VLCDs should be used only in a specialist setting as complications can include alterations in body composition, including bone loss and possibly loss of cardiac muscle.(9)
 
Drug treatment in obesity
The Royal College of Physicians has produced guidelines for use of antiobesity drugs.(10) The use of anti-obesity drugs like orlistat (Xenical; Roche) and sibutramine (Reductil; Knoll) may be appropriate for certain patients under medical supervision. If drugs are used, then the criteria outlined in the prescribing information should be followed. When orlistat is used for patients on insulin or sulphonylurea treatment, additional advice may be needed to prevent hypoglycaeemia. If used with metformin or acarbose, thre is the potential to aggravate gastrointestinal symptoms.

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References

  1. Amos AF, et al. The rising global burden of diabetes and its complications; estimates and projections to the year 2010. Diabetic Med 1997;14:S1-85.
  2. Tuomilheto J. Primary prevention of non-insulin dependent diabetes ­mellitus: a dream or reality? In: Alberti KGMM, Mazze RS, editors. Current trends in non-insulin dependent diabetes mellitus. Amsterdam: Elsevier Science Publishers; 1989.
  3. 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.
  4. Diabetes Prevention Program Research Group. Information of US National Institute of Diabetes and Digestive and Kidney Diseases; 2001. See www.prevent.diabetes.com
  5. Lean MEJ, et al. Obesity, weight loss and prognosis in type 2 diabetes. Diabetic Med 1990;7:228-33.
  6. UK Prospective Diabetes Study Group. Response of fasting plasma glucose to diet therapy in newly ­presenting type 2 diabetic patients (UKPDS 7). Metabolism 1990;39:905-12.
  7. Clinical Standards Advisory Group. Standards of clinical care for people with diabetes. Report of the CSAG Committee and the Government response. London: HMSO; 1994.
  8. Frost G. Comparison of two methods of energy prescription for obese non-insulin dependent diabetics. Practical Diabetes 1989;6:273-5.
  9. Uusitupa MIJ, et al. Effects of a very low calorie diet on metabolic control and cardiovascular risk factors in the treatment of obese non insulin dependent diabetics. Am J Clin Nutr 1990;51:768-73.
  10. Royal College of Physicians. Clinical management of overweight and obese patients with particular reference to the use of drugs. J R Coll Physicians Lond 1999;33:1.

Resources
Diabetes
UK
W:www.diabetes.org.uk 
Diabetes NSF
updates W:www.doh.gov.uk/nsf/ diabetes/index.htm 

Forthcoming event
25 April 2002
Delivering the Diabetes NSF:Abolishing the Boundaries
Central London
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