Diet and Nutrition Prevention of Chronic Diseases

6. Diabetes

• 6.1 Is diabetes a growing problem?
• 6.2 How can diet and physical activity affect diabetes?
• 6.3 What factors are known to affect diabetes?
• 6.4 How could diabetes be prevented?

6.1 Is diabetes a growing problem?

Diabetes is a disease that develops when the body is unable to produce or respond to insulin in the normal way. There are two types of diabetes.

Type 1 diabetes is less common and associated with a total lack of insulin. Previously known as insulin-dependent diabetes, it usually results from the destruction of the insulin-producing cells of the pancreas by the immune system. Both genetic and environmental factors seem to be involved in the onset of the disease.

Type 2 diabetes, previously known as non-insulin-dependent diabetes, accounts for most cases of diabetes worldwide. In this form of the disease, the body’s failure to respond to insulin in the normal way leads to the overproduction of insulin, which may result in a partial failure of the insulin producing cells of the pancreas and consequently insufficient insulin production.

Serious complications that can result from diabetes include blindness, kidney failure, amputation, infections, coronary heart disease and stroke. Lifestyle changes are key to both reducing the risk of developing and treating type 2 diabetes.

The number of cases of diabetes worldwide is currently estimated to be around 150 million. This number is expected to double by 2025. The condition, previously seen mostly in adults, is now affecting all age groups, including adolescents and children, especially in high-risk populations.

This text is a summary of: WHO/FAO Diet, Nutrition and the prevention of chronic diseases
Section 5.3 5.3.1 Background – 5.3.2 Trends 

6.2 How can diet and physical activity affect diabetes?

Genetic and environmental factors determine the likelihood of developing type 2 diabetes. The increase in number of cases appears to be due mainly to environmental changes, particularly lifestyle factors that contribute to weight gain and obesity.

The most dramatic increases occur in societies experiencing major changes in diet, reductions in physical activity, and where there are many overweight or obese individuals.

In all societies, overweight and obesity increase the risk of type 2 diabetes, especially when excess fat is stored in the abdomen.

This text is a summary of: WHO/FAO Diet, Nutrition and the prevention of chronic diseases
Section 5.3.3 Diet, physical activity and diabetes 

6.3 What factors are known to affect diabetes?

There is convincing evidence that excessive weight gain and excess fat in the abdomen increases the risk of developing type 2 diabetes. Excess fat in the abdomen is an important factor in the development of insulin resistance, a condition that underlies most cases of type 2 diabetes.

Children of mothers who are affected by diabetes during pregnancy are also at high risk of developing obesity and type 2 diabetes in childhood. Delayed growth in the womb and low birth weight may also increase the risk of developing resistance to insulin.

Overall, studies on humans indicate a probable causal link between saturated fatty acids and type 2 diabetes, and a possible causal association between total fat intake and type 2 diabetes.

In overweight people, voluntary weight loss enhances insulin sensitivity and reduces the risk of type 2 diabetes. Regular vigorous exercise may improve insulin sensitivity and thus reduce the risk of developing type 2 diabetes.

Table 9: Summary of strength of evidence on lifestyle factors and risk of developing type 2 diabetes

This text is a summary of: WHO/FAO Diet, Nutrition and the prevention of chronic diseases
Section 5.3.4 Strength of evidence 

6.4 How could diabetes be prevented?

Specific measures can be taken to reduce the risk for diabetes, especially efforts that focus on controlling weight and preventing obesity and cardiovascular disease. Measures include:

• Avoiding weight gain of more than 5 kg in adult life and treating excessive weight gain and obesity.
• Maintaining a mean Body Mass Index (BMI) in the range of 21-23 kg/m².
• Voluntary weight loss in overweight or obese people with higher than normal blood sugar levels.
• Engaging in at least a moderate level of physical activity for one hour or more in the course of the day on most days of the week. Exercising at 80 to 90% of maximum heart rate for at least 20 minutes five days per week may substantially improve insulin sensitivity
• Ensuring a low saturated fat intake.
• Consuming at least 20g of dietary fibre per day (i.e. whole grain cereals, fruit and vegetables).

This text is a summary of: WHO/FAO Diet, Nutrition and the prevention of chronic diseases
Section 5.3.5 Disease-specific recommendations