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Food for thought: the impact of diet & exercise on type 2 diabetes: a diabetes educators perspective

L. Spokes

Morgan Street HealthCare Clinic, 2/185 Morgan Street, Wagga Wagga NSW, 2650

Introduction

Diabetes is a global epidemic. Approximately 3% of the European adult population are diabetic and 5-10% of the North America adult population are also diabetic. Approximately 7.4% of the Australia adult population are diabetic while another 16.4% have impaired glucose tolerance. AusDiab also confirmed that there is at least one person undiagnosed diabetics for every person who is diagnosed Type 2 diabetes (Dunstan et al 2002). Currently, 1.2 million Australians have Diabetes and by 2010 Diabetes Australia expects the number to reach 1.8 million. Type 2 Diabetes is Australia’s fasting growing disease with 1,500 new diagnoses every week, and 214 diagnoses every day. Approximately 74,000 people have been diagnosed in the past year. More than 600,000 have been diagnosed in total with the remainder being still unaware of the problem. Globally, there are 150 million people with diabetes and this is expected to rise to 230 million by 2010, (Dunstan et al 2002).

Diabetes is a condition where there is excessive glucose in the blood. Glucose is the main source of energy for the body and comes from carbohydrate foods such as bread, pasta, rice, cereals, fruit and dairy products. The body digests these foods and glucose rapidly enters the blood stream and is acted upon by the hormone insulin. Glucose can be used quickly for energy or is stored in the body. Diabetes occurs when the body does not make enough insulin (Type 1 and in some cases Type 2) or when there is excess insulin (Type 2) and insulin resistance prevents the use and storage of the glucose correctly (Diabetes Australia, 2005).

People at risk of developing diabetes include: those over the age of 40; people with particular ethnic backgrounds; people who have a family history of diabetes and those who are overweight (particularly in the central region of their body); people who are inactive; and also those who have had previous gestational Diabetes (Couzos et al, 1998). People with any cardiovascular disorder such as hypertension or elevated lipids (e.g. cholesterol or triglycerides) or anyone that has been diagnosed as having impaired glucose tolerance which is a pre-diabetes diagnosis are also at risk of developing diabetes (Diabetes Australia, 2005).

Diabetes in Australia, obesity and lifestyle

Diabetes accounts for the sixth highest death rate by disease in Australia. People with diabetes are more likely to have high blood pressure, be obese and have elevated blood fats (e.g. cholesterol and triglycerides). They are 3 times more likely to have cardiovascular disease or a stroke. Renal disease accounts for 8%-14% of deaths in diabetics, 5% have foot ulcers and 3000 amputations are done every year on people with diabetes. Amputations are 15 times more common in people with diabetes and is the main reason for amputation in Australian hospitals. Approximately 15% of people with Type 2 diabetes have retinopathy at diagnosis with 55% developing over 10 years. Diabetes is the leading cause of blindness in the western world. Australia’s indigenous population has the 4th highest rate of Type 2 diabetes in the world (Diabetes Australia NSW 2005).

Obesity has been implicated in the cause of the increased incidence of diabetes. People overweight or obese have a high risk of developing Type 2 diabetes. It is estimated that 67% adult males and 52% adult females in Australia are overweight and this has increased by about 1% a year since 1980. Table 1 shows the percentage of adult males and females in the different age groups who were overweight in 2000 (Dunstan et al, 2002).

Table 1. Percent adults overweight in different age groups in 2000.

Age (years) / er cent

Adults

25-34

35-44

45-54

55-64

65-74

>75

Total

Male

60.5

64.2

72.4

74.0

73.1

63.8

67.4

Female

35.1

44.5

58.1

67.6

68.9

52.2

52.0

All

48.1

54.4

65.3

70.8

70.8

57.1

59.6

(Source: International Diabetes Institute: Diabesity and Associated Disorders in Australia 2000: The Australian Diabetes, Obesity and Lifestyle Study)

The following strategies are recommended to reduce the complications caused by high blood glucose and diabetes:

1. Healthy Eating: Eat a wide variety of nutritious foods, carbohydrates low in GI (Dietary Guidelines for Australian Adults)

2. Exercise regularly: Thirty minutes of moderate exercise daily (e.g brisk walking) are currently recommended. Eighty minutes of exercise will soon be the recommendation.

3. Stop smoking

4. Limit alcohol intake to 1 standard drink per day on average and no more than 6 on any one day. Two days a week should be alcohol free.

5. Maintain healthy body weight. Healthy BMI is 18.5-24.9 kg/m with waist, 94cms (men) or, 80cms (women) (Carey et al. 1996)

BMI can be determined as follows:

BMI = weight in kg

(height in meters)2

It is important for diabetics to be active and exercise, as it will help reduce the effects of Type 2 diabetes. As little as 30 minutes of walking, swimming, cycling, or jogging every day is beneficial. All upper body resistance exercises are beneficial and even chair walking can help and improve one’s well being. Exercise reduces insulin resistance, improves circulation, reduces blood and glucose levels and improves lipid levels. Exercise has very good overall long-term health benefits as it can improve mental health, strengthen muscles and help control weight. Most of all, exercise sets a good example for the next generation.

DIET

Short-term experimental studies suggest that, potentially, a high GI diet, which has a large amount of refined grains, plays a major role in the development of obesity (Ludwig et al, 1999). It is the educator’s role to help clients to understand Glycemic Index (GI) as taking charge of their diet has a huge impact on long-term health outcomes.

The Glycemic index (GI) is a physiological measure of carbohydrate (gram for gram) based on their immediate effect on blood glucose levels (Brand-Miller et al, 2002). Carbohydrates that break down quickly during digestion have a high GI value. GI is simply a carbohydrate ranking of food groups according to the glucose response and impact on blood glucose. Carbohydrates that break down slowly release glucose gradually into the blood stream and have a low GI while others release glucose very fast and have a high GI (Brand-Miller et al, 2002).

However, GI cannot capture the entire glucose-raising potential of a dietary carbohydrate as glucose response is influenced not only by the GI value but also the amount of carbohydrate which is accounted for by the term Glycemic Load (GL). Glycemic Load incorporates both quality and quantity of carbohydrate consumed, and white bread is used as a reference food (Salmeron et al, 1997b; Liu 1998 and Liu et al, 2000).

Low GI does not mean not eating carbohydrates as there are many benefits of whole grains in the diet that are low in fat and high in fibre. Whole grains can be beneficial in weight control. High fibre grain foods prevent weight gain by increasing appetite control through delay in carbohydrate absorption (Porikos et al, 1982). Whole grains lower post prandial (after meals) blood glucose levels and fasting insulin levels. This alone may lead to weight loss, especially among the overweight (McKeown et al, 2002). Epidemiological studies have consistently linked whole grains to lower fasting insulin levels and glycemic response (Jenkins et al, 1986. Periera et al, 1998, Fung et al, 2001, McKeown et al, 2002). The Framingham offspring study of 2,943 men and women, observed fasting insulin concentrations were lower in those with a higher intake of whole-grain food. This was especially evident in the overweight and obese participants (McKeown et al, 2002).

Data from a number of sources has indicated that a high intake of rapidly absorbed carbohydrates, such as refined grains and potatoes, are associated with a much higher risk of obesity and chronic disease. Reducing processing such as milling may offer a simple and important answer to helping manage diet and alleviate some of the burden of Type 2 diabetes is placing on developing countries.

Conclusions

Consumers (particularly older people) need palatable grains as they need to be able to eat whole grains without over processing. Food labels need to be easy to understand with simple nutrition information panels. The print needs to be larger so that older consumers with poorer eyesight can read them. The cost of whole grain food needs to be reduced to encourage greater consumption. Whole grain products should also be easily accessible in the supermarket. The role of the diabetes educator is extremely import. They must interpret all the information available and get the message out to their client as it is an important message. Too many clients, when asked about learning GI, comment on how good it will be to have that green cordial back again!

References

Brand-Miller J, Foster-Powell K, and Colagiuri S, (2000). The New Glucose Revolution; printed by Holder Headline Australia Pty. Ltd. Kent Street Sydney.

Carey DG, Jenkins AB, Campbell LV, Freund J and Chisholm DJ (1996). Diabetes 45: 633-8

Couzos S, Metcalf S, Murray R, O’Rourke S. (1998). Systemic review of existing evidence and primary care guidelines on management of non-insulin dependent diabetes in Aboriginal and Torres Strait Islander Populations. Office for Aboriginal Health services, CDHFS Canberra , ACT.

Diabetes Australia (2005) www.diabetesaustralia.com.au

Dunstan DW, Zimmet PZ, WelbornTA, deCourten MP, Cameron AJ, Sicree RA, Dwyer T, Colagiuri S, Jolly D, Knuiman M, Atkins R, Shaw JE (2002) on behalf of AusDiab Steering Committee. The rising prevalence of diabetes and impaired glucose tolerance. The Australian Diabetes, Obesity and Lifestyle Study. Diabetes Care; 25:829-34

Fung TT, Rimm EB, Spiegelman D, Rifia N, Tofler GH, Willett WC and Hu FB (2001). Am. J. Clin, Nutr. 73:61-67

Jenkins DJ, Wolever TM, Jenkins AL, Giordano C, Giudici S, Thompson LU, Kalmusky J, Josse RG and Wong GS (1986). Am. J. Clin. Nutr. 43:516-520

Liu S, (1998). Proc. Nutr. Soc. Aust. 22:140-150.

Liu S, Manson JE, Stampfer M, Holmes DM Hu FB, Hankinson SE and Willett WC (2000). Am. J. Clin. Nutr 73:560-566

McKeown N, Meigs J, Liu S, Wilson P and Jacques P. (2002). Am. J. Clin. Nutr. 76: 390-398

Periera M, Jacobs D, Slatery M, Ruth K, Van Horn L, Hillner J and Kushi L, (1998). Diabetes 44(suppl.):A40

Porikos KP, Hesser MF and Van Itallie TB (1982). Physiol. Behav. 29:293-300

Salmeron J, Manson JE, Stampfer MJ, Colditz GA, Wing AL and Willett WC (1997). JAMA 277:472-477

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