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Managing diabetes through diet

Mina Crisp
DipDietetics SRD
Senior Dietitian
Mid Staffordshire General Hospitals NHS Trust

Adult obesity in the UK has more than doubled in the last 20 years; 17% of adult men and 20% of adult women are now obese.(1) If this trend continues, one quarter of the British population will be obese by 2010.(2) Fifty percent of those who are obese will have at least one associated health problem.(3)
 
The problem for diabetes
More than 80% of patients with type 2 diabetes are overweight at diagnosis. However, central obesity is more closely related to type 2 diabetes than just being overweight. Central adipose tissue has different metabolic properties than peripheral fat and causes greater insulin resistance.(4) This leads to the common clinical scenario for patients to have an increasing HbA(1c) - a long-term measure of diabetic control. This is often managed by increasing medication to improve glycaemic control. Most medical intervention leads to increased appetite and weight gain. This increasing insulin resistance causes further deterioration in HbA(1c) - a nightmare cycle for the patient. The challenge for the health professional is to break this cycle. Our task is to advise, inform, educate and support the diabetic patient to choose an appropriate treatment plan to achieve the best glycaemic control with suitable diet and weight management.
The National Service Framework for Diabetes:Standards (England and Wales) 2002 states that: "The provision of information, education and psychological support that facilitates self-management is the cornerstone of diabetes care. People with diabetes need the knowledge, skills and motivation to assess their risks, understand what they will gain from changing their behaviour or lifestyle and to act on that understanding by engaging in appropriate behaviours." (5) 
To achieve this standard of care every PCT is expected to have a structured multidisciplinary education programme for patients with type 2 diabetes by April 2006.
 
Weight management 
BMI or waist circumference?
It is well documented that:

  • Visceral fat is a metabolically active tissue that contributes to the development of multiple metabolic disorders, including diabetes.(6)
  • Waist circumference is a better predictor of cardiovascular risk (CV) than body mass index (BMI).(7,8)
  • Waist circumference can therefore be an effective tool for assessing CV risk.(9,10)

Use a tape measure to assess health risks:
    - Measure waist at a midpoint between the lowest rib and the iliac crest, while thepatient is breathing out.
    - Ideal waists:     male                                female Although achieving a normal BMI or waist measurement for each patient is ideal, significant improvement in diabetic control and reduction in mortality can be attained with weight loss of just 10%.(11)

  • Mortality:

         >20% fall in total mortality.
         >30% fall in diabetes-related deaths.
         >40% fall in obesity-related cancer deaths.

  • Diabetes fall of 50% in fasting glucose.

Diet and diabetes
Diet and exercise are the cornerstones of diabetes management. There is no doubt that diet helps to improve symptoms of both hypo- and hyperglycaemia and also aids in the prevention of long-term complications, including renal failure, blindness, amputations and coronary events. (12,13,14) The objectives of dietary treatment are:

  • Maintain blood glucose levels as near normal as possible by balancing food intake with oral hypoglycaemic agents, insulin and activity levels.
  • Achieve optimal serum lipid levels.
  • Adjust energy intake to achieve reasonable weight targets.
  • Improve overall health through optimal nutrition.

It is now accepted that there is no "diabetic diet". Healthy eating is recommended for everyone.

What is a healthy diet for diabetes?
The Balance of Good Health chart (see Figure 1) has been produced by the Food Standards Agency as a guide that aims to help people to understand and enjoy healthy eating. It is recommended that this is used only as a guide for patients with diabetes.

[[NIP27_fig1_38]]

The glycaemic index (GI)
The glycaemic index (GI) is a ranking of carbohydrate containing foods based on the rate at which they raise blood sugars. A slower response may facilitate better glycaemic control and lipid profiles in people with diabetes. (15,16) Foods with a lower GI also elicit a greater satiety (see Box 1).

[[NIP27_box1_40]]

Practical applications of the GI:

  • Opens the way to greater flexibility and variety of foods consumed.
  • GI should not be used in isolation, but incorporated with current diet.
  • GI changes with food combinations and cooking methods.
  • Use GI in the overall balance of combination of meals and not as individual foods.

Potential benefits of lower GI foods:

  • Helps to maintain more even blood glucose profiles, avoiding "hypos".
  • Reduces peaks in blood sugars following meals.
  • Benefits weight loss due to increase in satiety levels and varied diet (see Box 2).

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Empower patients to choose their own diet
Many diet programmes and adverts promise a "quick fix" of rapid weight loss. These are often unscientific and may be harmful. The challenge is not just getting to, but maintaining, a healthy weight in the long term.
 
Avoid crash diets and fad diets, and stick to well- recognised diet programmes, such as WeightWatchers or Slimming World. These can be advised or even offered in GP practices with careful supervision by a dietitian. Look for one that:

  • Only promotes weight loss of 0.5-1kg (1-2lb) a week.
  • Encourages guidelines for healthy eating - a balanced, varied diet that incorporates all major food groups.
  • Is realistic and flexible enough so that it is sustainable - no extreme hunger or elimination of food groups.
  • Encourages moderate exercise and increased activity levels.
  • Helps the patient to modify their lifestyle and think about food, so they can maintain a target weight once it has been attained.

Tips for controlling calories

  • Ask patients to keep a food diary for a week, writing down everything they eat and drink. People who are overweight often don't realise how much they are eating.
  • Advise patients to use the food diary to find ways of cutting down calories. For instance, changing the balance of foods on the plate, for example having less cheese or meat and more salad with the meal. Or by cutting out a regular snack food and replacing it with a piece of fruit.
  • Don't forget that drinks count towards the daily calorie intake. Alcohol is high in calories - three pints of beer could add up to 600 calories. Sugary drinks should be avoided.
  • Patients should aim to do 30 minutes of moderate physical activity on most days of the week. Moderate activity is where one feels slightly warm and out of breath - brisk walking is ideal, encourage taking stairs at work instead of the lift, and walking to the shops instead of taking the car.

If not healthy eating, then what?
For those patients who need intensive weight management there are other alternatives available. However, all these need regular follow-up and support.

Some areas of the country now offer these as part of the diabetes treatment, but these are mainly in the hospitals.

  • Very low-calorie diets (VLCDs) or low-calorie diets (LCDs) include the Cambridge Diet Plan, Slimfast and other tailored diets. They are mainly used as meal replacement programmes, which can be used to great benefit for people with type 2 diabetes.(17) Most of the products contain full nutrition and do not affect the patients adversely. Patients on these programmes need to be monitored closely for medication changes due to the decrease in carbohydrate. Further information about these programmes and their application is available from the individual websites or the appropriate manufacturer.

Drug intervention can be used if other methods of weight loss fail. This includes:

  • Orlistat (Xenical) - this is an oral prescription that works in the gut. It prevents the fat from the diet being absorbed. The undigested fat is eliminated in the faeces.
  • Sibutramine - This drug is thought to work by increasing the activity of certain chemicals, norepinephrine and serotonin, in the brain.

Both these medications need to be used as part of an overall treatment plan and not as an isolated treatment. Both have been reviewed by NICE with specific recommendations.(19)

Bariatric surgery provides good results in selected patients. However, it should not be seen as a "quick fix" solution and should be regarded as a last resort. Patients need careful assessment by multidisciplinary teams that should include a dietitian, psychologist and surgeon. Long-term follow up is essential as patients are at risk of nutritional problems, particularly after Roux-en-Y gastric bypass. The diet after surgery is restrictive, and not all patients will be able to commit to it.

Conclusion
Diabetes is a deteriorating condition, and one that we, as health professionals, and our patients find very frustrating. Returning to a normal BMI and waist measurement may be ideal, but patients need to understand that even some weight loss confers great benefit to the control of diabetes. Treatment regarding weight management and diet is only one aspect of the long-term management of type 2 diabetes. To ensure a successful outcome, it is of the utmost importance that we advise and support our patients in making the relevant changes to their lifestyle and health.

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References

  1. Prescott-Clark P, Primatesta P. Health survey for England. London: HMSO; 1999.
  2. Jebb S. Weight of the nation - obesity in the UK. A report commissioned by the Bread of Life Campaign. London: Flour Advisory Bureau; 1999.
  3. Office of Population Censuses and Surveys. Morbidity statistics from general practice 1981-2: Third National Study. London: HMSO; 1986.
  4. Haffner SM. Diabetes Care 1999;22.
  5. DH. The National Service Framework for Diabetes: delivery strategy. London: DH; 2002.
  6. Pouliot MC, et al. Am J Cardiol 1994;73:460-8.
  7. Frayn K. Int J Obes Relat Metab Disord 1997;12:1191-2.
  8. Frayn KN et al. Int J Obes Relat Metab 2003;27:875-88.
  9. Pouliot MC, et al. Diabetes 1992;41:826-34.
  10. Zhu S, et al. Am J Clin Nutr 2002;76:743-9.
  11. Royal College of Physicians, Royal College of Paediatrics and Child Health, Faculty of Public Health. Storing up problems: the medical case for the slimmer nation. Report of a working party. London: RCP; 2004.
  12. UKPDS. Metabolism 1990;39:905-12.
  13. Lean MEJ, et al. Diabet Med 1990;7:129-33.
  14. Jones K, et al. Practical Diabetes 1989;6:18-9.
  15. Frost G, et al. Diabet Med 1994;11:397-401.
  16. Fontvieille AM, et al. Diabetes Nutr Metab 1988;1:139-43.
  17. Paisley RB, et al. Diabet Med 1998;15:73-9.
  18. Mustajoki P, Pekkarinen T. Very low energy diets in the treatment of obesity: Obesity reviews. Vantaa, Finland: Peijas Hospital, Dept Medicine; 2000.
  19. NICE. Technology Appraisal guidance No 30/32. London; NICE: 2003.