5. Diabetes is Just the Tip of the Iceberg #Diabetes #Dementia

Those who suffer from diabetes are have a increased risk of developing a range of many other diseases and conditions. These can include damage to small blood vessels which in turn leads to blindness, kidney failure and nerve damage.  Deterioration of the larger arteries can contribute to stroke and heart disease as well as causing difficulties in pregnancy and infection. The American Heart Association has concluded that adults with diabetes are two to four times more likely to have heart disease or a stroke than adults without diabetes.

In a 12-year study the effect of diabetes on death rates in men aged 35 and 57 years was assessed. The results showed that those with diabetes were 3 times more likely to die than those without, which confirms that diabetes is a strong independent factor for heart disease, stroke and all-cause mortality(1).

Information from the US based on the National Health Interview Surveys has been used to calculate the impact of diabetes on public health. Of 356,787 respondents surveyed between 1984 and 2000 there were 14,325 cases of diabetes diagnosed. It was concluded that for individuals born in 2000, the life-time risk of developing diabetes was 38.5% in women and 32.8% in men. This is considerably higher than for many other diseases and conditions. For example in the US the risk of women developing breast cancer is 1 in 8 (12.5%). Children who are diagnosed with diabetes at age 10 will have their life expectancy reduced by about 20 years. A man diagnosed with diabetes at age 40 will lose almost 12 years of life and 19 Quality Adjusted Life Years (QALYs) compared with a person without diabetes. A woman of the same age will lose about 14 years of life and 22 QALYs(2).

In the USA, detailed information on health and nutrition has been collected by the National Health and Nutrition Examination Surveys (NHANES). An analysis shows how the death rate in diabetics is much higher than those due to all causes (Table 1). In men both rates have fallen progressively in successive surveys. However in women although the all-cause death rate has declined there has actually been a substantial increase in the death rate for diabetics in the most recent survey(3).

TABLE 1

DEATH RATES IN THE USA

A more recent study has compared the death rates between people with and without diabetes (mean age 55 years). This is based on 820,000 participants of which 40,116(6%) had diabetes. Over an average period of 13.6 years 123,305 deaths were recorded. The results (Table 2) show that in men with diabetes the death rate was 2.5 times greater than those who were free of diabetes. The corresponding value for women was 3.This study confirms that those with diabetes have a greatly increased risk of dying from cardiovascular diseases but also identify greater risks from certain cancers especially of the liver, pancreas, ovary, colorectum and bladder. Other conditions with an increased risk were renal disease, infections, digestive disorders and pneumonia. The reduction in life expectancy for men and women is shown in Table 3(4).

TABLE 2

EFFECT OF DIABETES ON DEATH RATE IN ADULTS

TABLE 3

YEARS OF LIFE LOST DUE TO DIABETES

The Multinational Monitoring of Trends and Determinants in Cardiovascular Disease (MONICA) project was conducted under the auspices of the WHO. Information from participants located in Northern Sweden was used to compare the incidence of stroke in diabetics and non-diabetics over the period 1985-2003. There were 15,382 men and 5,895 women aged between 35 and 74 who had suffered a stroke. It was found that diabetic men were 5 times more likely to experience a stroke than non-diabetics. For women there was an 8-fold difference(5).

Epidemiological studies show that there is a remarkable degree of consistency between the risk factors for colon cancer and diabetes which include a high BMI, physical inactivity and a high consumption of carbohydrates especially sugars. The geographic patterns for both diseases are very similar which suggests that there is a common cause(6).

Therefore it is not at all surprising that in Great Britain the life-time risk of developing bowel cancer in men has increased from 3.5% in 1975 to 6.9% in 2008. In women there has been an increase from 3.9% to 5.4% over the same period. There has also been an increase in the incidence of breast cancer in females aged between 40 and 59 years which have increased from 134/100,000 in 1979 to 215/100,000 in 2008(7).

A study conducted in Rotterdam has found that those with diabetes were over 3 times as likely to develop dementia as those without. Patients being treated with insulin were at greater risk of dementia by a factor of 4(8).

Those with undiagnosed diabetes were more than 3 times as likely to develop AD compared with those free of diabetes(9).

The differences in the incidence of disease in diabetics is probably even greater than indicated in the various studies because those classed as “non-diabetics” invariably include diabetics which have not been diagnosed. This means that the values for those considered free of diabetes would be higher than those who are genuinely free of the disease.

Although these findings do not prove that diabetes is actually the cause of the various diseases it is highly likely that there is a common factor and if this can be identified and controlled effectively there is the potential for enormous improvements in the standards of public health.

REFERENCES

1. J Stamler et al (1993) Diabetes Care 16 (2) pp 434-444

2. K M V Narayan et al (2003) Journal of the American Medical Association 290 (14) pp 1884-1890.

3. E W Gregg et al (2007) Annals of Internal Medicine 47 (3) pp149-155

4.The Emerging Risk Factors Collaboration (2011) New England Journal of Medicine 364 (9) pp829-841

5. A Rautio et al (2008) Stroke 39 pp3137-3144

6. E Giovannucci (2001) Journal of Nutrition 131 (11 Suppl) pp 3109S-3120S

7. Cancer Research UK

8. A Ott et al (1996) Diabetologia 39 (11) pp 1392-1397

9. W L Xu (2009) Diabetologia  52 (6) pp 1031-1039