350 Million Adults Have Diabetes After Explosion in Prevalence Spanning Three Decades

An estimated 350 million people in the world have diabetes, according to a major new international study published Online First by The Lancet. The study shows that diabetes prevalence has risen (in many cases sharply), or at best remained unchanged, in virtually every part of the world during the past three decades. The Article authors are Professor Majid Ezzati, Imperial College London, UK, and Dr Goodarz Danaei, Harvard School of Public Health, Boston, MA, USA, and colleagues.

Patients with diabetes have inadequate blood sugar control. This can lead to heart disease and stroke, as well as damage to the kidneys, nerves, and the retinae. High blood glucose and diabetes cause some 3 million deaths globally each year, a number that will continue to rise as the number of people affected increases.

The researchers analysed fasting plasma glucose (FPG) data from 2.7 million participants aged 25 and over across the world, and used advanced statistical methods to estimate prevalence. They found that the number of adults with diabetes increased from 153 million in 1980 to 347 million in 2008. This is considerably higher than a 2009 study that estimated 285 million adults globally had diabetes. While 70% of this rise was due to population ageing (ageing increases the risk of diabetes), the other 30% was due to higher prevalence across different age groups, caused by increases in risk factors such as obesity. The percentage of male adults with diabetes worldwide rose from 8.3% to 9.8% (an 18% rise) across the three decade period, with adult female prevalence increasing from 7.5% to 9.2% (a 23% increase).

To test whether or not someone has diabetes, doctors measure the levels of glucose in a patient's blood after they have not eaten for 12 to 14 hours, since blood sugar rises after a meal. FPG below 5.6 millimoles per litre (mmol/L) is considered normal, above 7 mmol/L is diagnostic of diabetes and an FPG level between 5.6 and 7 is considered pre-diabetes. This new study found mean global FPG had risen in both men and women.

Among high-income countries, the USA saw FPG rise at more than the twice the rate of Western Europe over the three decades. In these wealthy nations, diabetes and glucose levels were highest in USA, Greenland, Malta, New Zealand and Spain, and lowest in the Netherlands, Austria and France. Despite its obesity epidemic, the UK's diabetes prevalence was lower than that of most other high-income countries. In a league of 27 western high-income countries, British men were 5th best (or had the 5th lowest diabetes rates), while British women were 8th best.

Globally, diabetes has taken off most in Pacific Island nations. In states such as the Marshall Islands, one in three women and one in four men have diabetes. Saudi Arabia also reported very high rates. Glucose and diabetes were also particularly high in south Asia, Latin America, the Caribbean, Central Asia, North Africa and the Middle East. The region with the lowest glucose levels was sub-Saharan Africa, followed by east and southeast Asia. Eastern Europe's diabetes prevalence, while not low, changed little over the three decade period.

The authors noted a strong correlation between increasing diabetes prevalence and rising body-mass index trends worldwide—a correlation higher for women than for men. But they say: "However, genetic factors associated with ethnic origin, fetal and early life nutritional status, diet quality, and physical activity might also affect glycaemic values and trends [and therefore diabetes prevalence]."

Professor Ezzati adds: "Diabetes is one of the biggest causes of morbidity and mortality worldwide. Our study has shown that diabetes is becoming more common almost everywhere in the world. This is in contrast to blood pressure and cholesterol, which have both fallen in many regions. Diabetes is much harder to prevent and treat than these other conditions."

Dr. Danaei adds: "Unless we develop better programmes for detecting people with elevated blood sugar and helping them to improve their diet and physical activity and control their weight, diabetes will inevitably continue to impose a major burden on health systems around the world."

In a linked Comment, Dr Martin Tobias, Health and Disability Intelligence, Ministry of Health, Wellington, New Zealand, concludes: "Worldwide...the urgent need is to strengthen basic surveillance of dysglycaemia and diabetes, including standardised frameworks, case definitions, survey methods, tools, and reporting protocols. The forthcoming high-level meeting of the UN General Assembly on the Prevention and Control of Non-communicable Diseases (New York, Sept 19-20, 2011), provides a welcome opportunity to strengthen global commitment to non-communicable disease surveillance."