GI News Briefs

Unite for Diabetes
During the last 20 years, the total number of people worldwide with diabetes has risen from 30 million to 230 million according to the International Diabetes Federation. The number is expected to reach 350 million by 2025. The top five countries with the most diabetes sufferers in 2003 were India 35.5 million, China 23.8 million, USA 16 million, Russia 9.7 million and Japan 6.7 million.

Facing the facts:

• There are 6 million new diabetes sufferers in the world each year.
• Half of all diabetes sufferers around the globe do not know they have it. In some parts of the world 80% of sufferers don’t know.
• Diabetes raises the sufferer’s risk of developing a cardiovascular disease by two to four times. Cardiovascular disease, the number one cause of death in the industrial world, will soon be the number one cause of death globally.
• Diabetes is now the fourth biggest cause of death worldwide.
• Every ten seconds someone in the world dies as a result of having diabetes – 3 million deaths a year.
• Good control of blood glucose levels significantly reduces the diabetes patients’ risk of developing complications. Managing hypertension and raised blood lipids is also crucial.

Diabetes is threatening to overwhelm future medical services if left unchecked. The International Diabetes Federation (IDF) is leading a worldwide ‘Unite for Diabetes’ campaign to have the United Nations recognise the global burden of diabetes. Why a UN resolution? If governments begin now by promoting low-cost strategies to alter diet, increase physical activity and modify lifestyles, the advance can be reversed. The proposed resolution would recognise the need for prevention and acknowledge the special needs of children and adolescents, the elderly, pregnant women, migrant populations and indigenous peoples. The aim is for the UN Resolution to be declared on World Diabetes Day 2007 (November 14). For more information about the campaign, visit www.unitefordiabetes.org.
– International Diabetes Federation Press Release from the American Diabetes Association’s 66th Scientific Sessions

The Rice Factor
Heart disease and diabetes are serious health problems in Japan just as they are in many other parts of the world. In fact, heart disease is the second leading cause of all deaths and more than 6.7 million people in Japan have diabetes. Will adopting a low GI or low GL diet reduce the risk? So far, most studies showing the beneficial effects of low GI and GL diets have been carried out in the US, Europe and Australia with people who eat western diets. What happens in Asia where rice is the staple? In Japan, for example, rice contributes 43% to total carb intake and 29% to energy intake (calories).

Japanese researchers have found positive correlations between dietary GI and body mass index, serum triglyceride levels, fasting plasma glucose and HbA1c; and between GL and serum triglyceride levels, fasting plasma glucose and decreased levels of high-density lipoprotein (HDL), or good, cholesterol. They published the results of their cross-sectional study of 1354 healthy Japanese women eating a traditional diet based on a self-administered diet-history questionnaire in AJCN (May 2006). The main contributor to the GI and GL of the women’s diet was white rice (59%) followed by confectionary (11%), fruit (7%), sugars (6%), bread (4%), noodles (3%), other rice (3%), and potatoes (3%). The authors make the point that although the results may not be extrapolated into the general Japanese population (the subjects were selected Japanese female farmers), they should ‘provide valuable insight from a prevention perspective.’
– Am J Clin Nutr 2006;83: 11161–9

Fortelling Early Insulin Resistance
‘Insulin resistance not only predisposes individuals to type 2 diabetes, it is also a major risk factor for cardiovascular disease,’ says Timothy Graham, MD, a researcher at Beth Israel Deaconess Medical Center (BIDMC). ‘In the clinical setting however, it is often difficult to distinguish individuals with and without insulin resistance.’ Insulin resistance develops when the body’s muscles, fat and liver cells lose the ability to respond to the hormone insulin.

Elevated levels of a molecule called retinol-binding-protein-4 (RBP4) can foretell early stages of insulin resistance, a major cause of type 2 diabetes as well as heart disease, reveal BIDMC researchers writing in The New England Journal of Medicine.

The researchers were looking to see whether levels of RBP4 correlated with the presence or absence of insulin resistance in three groups and they repeated the measurements after exercise training for one group. They found that RBP4 levels were higher in all cases in which insulin resistance was high. Elevated RBP4 was also closely associated with increased BMI, waist-to-hip ratio, serum triglyceride levels, and systolic blood pressure, as well as decreased levels of high-density lipoprotein (HDL), or good, cholesterol. All the people who improved their insulin sensitivity with exercise also lowered their serum RBP4 levels. Among the third who did not improve their insulin sensitivity, neither did their RBP4 levels go down.

Dr Barbara Kahn

Barbara Kahn, MD, Chief of the Division of Diabetes, Endocrinology and Metabolism at BIDMC and Professor of Medicine at Harvard Medical School says: ‘Collectively, these findings tell us that RBP4 is a useful marker for therapeutic improvement and that this protein could play a causal role in insulin resistance in humans. Because RBP4 levels consistently corresponded with insulin resistance – even among lean subjects whose genetic risk for the development of diabetes might otherwise be overlooked – this protein could be an important marker for type 2 diabetes among the general population. Being able to determine diabetes risk well before the onset of symptoms could provide an important opportunity for patients to take preventive measures,’ she adds. ‘For those who are overweight or sedentary, this could mean making changes to their diet and fitness routines. For those who are lean and fit, but have a family history of type 2 diabetes, this could mean taking antidiabetic medication. Either way, these findings could help clinicians to better manage this growing epidemic.’
– NEJM 354:2552–2563; BIDMC Press Release

GI: The Real Meal Deal
Recent criticism of the GI has focused on unpredictable outcomes of blood glucose values in meals because of variations in fat, protein and fibre levels.

Researchers in the University of Toronto’s Department of Nutritional Sciences and the University of Sydney’s Human Nutrition Unit have some reassurance for people with diabetes and carb-counters. The glycemic index (GI), the table that lists the quality of carbohydrates in more than 750 common foods, works just as predictably whether subjects consume a single portion of one item, or a normal meal. ‘The good news it that the GI index works’ says Prof. Tom Wolever. ‘For sensible people it makes a lot of sense. It’s simple proportional measure – like mixing paint.’

Concerned about the methodology of recent studies done elsewhere showing unpredictable responses, Wolver and his associate, Prof. Jennie Brand-Miller of the University of Sydney, each conducted studies on two groups of healthy subjects. Fourteen different test meals were used in Sydney and Toronto, and the food combinations reflected typical breakfast choices such as juice, bagels and cream cheese, etc. Despite the variations in food, blood glucose responses remained consistent with GI measures.

‘We had previously done much smaller studies. We revisited the question, using more meals and variety in two different centres with judiciously selected foods. I was startled by the degree of predictability,’ says Wolever. ‘The carbohydrate, fat and protein composition of the meals varied over a wide spectrum. The glucose responses varied over a five-fold range range, and 90 per cent of the variation was explained by the amount of carbohydrate in the meal and the GI values of the foods as given in published GI tables. The concept works.’ The results are published in the June issue of the American Journal of Clinical Nutrition.
– Am J Clin Nutr 2006;83:1306–12; University of Toronto press release