"DIABESITY"
Studies show fat and sugar are a bad mix
By Dr. Sheila Alcantara
Accumulating too much fat is a slow and steady means to one's grave. Not only is it wrought with so many attendant complications, medical or otherwise, there is also that already long list of chronic diseases patients are at risk of contracting. One particularly established worrisome association is the link between obesity and diabetes.
Foremost Filipino endocrinologist Augusto Litonjua calls it diabesity, after Paul Zimmet of Australia, if only to emphasize the intimate relationship between these two disorders of modern times. And when this deadly duo strikes, the costs can only be staggering.
Twin Epidemics
In a culture that fosters faulty eating habits and almost nil physical activity, it is not surprising that obesity has become a major public health problem, now affecting nearly 60 million adults in the United States. However, it was only in the past decade that public health officials noted the parallel increase in the prevalence of diabetes and obesity.
In a Centers for Disease Control and Prevention (CDC) study published in the Journal of American Medical Association, researchers noted that during the 1990s a 49-percent rise in the number of diabetics accompanied a 61-percent increase in the number of obese Americans. The trend cut across all demographic and geographic segments of the population, with Mississippi having the highest rate of both obesity and diagnosed diabetes. In a follow-up study reported in the same journal, the twin epidemics were noted to escalate even further, with obesity climbing again, from 19.8 to 20.9 percent from 2000 to 2001 while the number of diabetics went up from 7.3 to 7.9 percent. This continuing rise in the incidence of both disorders already represents a major public health burden, with health-care costs on diabetes alone already amounting to a whopping $98B in 1997.
On the other hand, Litonjua, speaking in a recent forum on diabesity, said that by far, the most telling evidence that links diabetes to obesity is the result of the International Survey of the Prevalence of Diabetes. It shows that high mean body weights associated with increased prevalence of diabetes were only seen in affluent countries. In places like Bangladesh and Malaya, however, where the number of diabetics is much lower, such trends do not exist.
Where the Fat Is
While total body fat is an independent risk factor for diabetes, where it is located is equally important. In particular, it is the adipose tissue found predominantly in the abdominal area that adds to the risk of high blood sugar levels. Therefore, if a person is obese, and the heaviness is located in his waist, the chances of being diabetic are much higher than when someone is just simply overweight.
What's special about the fat that people with muscular abs do not possess is that intra-abdominal fat cells are especially sensitive to the effects of the sympathetic nervous system. Hence, these can be easily mobilized to break down complex triglycerides into simple fats, which are delivered to the liver. Too much fatty acids in the liver, in turn, inhibit the breakdown of insulin, that all-too important hormone that breaks down sugars. This leads to high insulin levels, and hence, insulin resistance-the hallmark of type 2 diabetes. Abdominal fat can be determined by the waist-hip ratio, in the same way that total body fat is measured by the body mass index.
The Missing Link
The close connection between diabetes and obesity became all the more clearer with the discovery of the protein resistin. Announced in the journal Nature by researchers from the University of Pennsylvania School of Medicine, the group of Mitchell Lazar discovered what might yet be the missing link between the two conditions. Resistin, short for "resistance to insulin," is produced in fat cells, and tends to be produced at higher levels in diabetic mice with both diet-induced and hereditary obesity. It was also shown that anti-diabetic drugs lowered resistin levels, and when anti-resistin antibodies were administered, greater glycemic control was achieved in mice on high-fat diet.
Although the exact mechanism of the development of diabetes in obese people remains yet to be fully established, the prospect of its role in the obesity-diabetes link seems truly promising, and it is envisioned that drugs targeting this hormone can be developed to ease the burden of the disease in the near future.
Keeping It Low
Obesity, in all its myriad forms, tends to make everything worse, especially as far as diabetes is concerned. At its most elemental form, obesity alone can predispose a person to type 2 diabetes. On the other hand, patients who are fat and become pregnant have increased risk for acquiring diabetes during pregnancy. For those who are already diabetic and then become obese, the requirement for antidiabetic drugs is further increased, while in patients who are already both diabetic and obese, the risk for cardiovascular complications become even higher.
If indeed obesity wreaks havoc on the body's blood sugar controls, then it is quite logical to conclude that losing weight can somehow improve glycemic levels. The combined effects of lifestyle changes, including exercise and healthy diet, were explored in a recent study by a team of experts from Harvard. Published in the New England Journal of Medicine, the study found that being overweight or obesity is the single most important predictor of diabetes in the nearly 85,000 female nurses followed for occurrence of diabetes for 16 years.
On the other hand, various studies have shown that these benefits of weight loss can be translated clinically into reduced long-term (glycosylated hemoglobin) and day-to-day blood sugar levels. Keeping the total body fat low also lowers bad cholesterol while increasing good cholesterol levels. Even diastolic pressure goes down. The overall prevalence of diabetes is therefore lowered, as was shown by independent research in Finland, Sweden, and China.
While it is truly favorable for the obese to shed some weight, the deadly tandem with obesity in the diabetic makes it even more difficult for these patients to lose weight. Of course, the natural history of type 2 diabetes itself predisposes to weight gain. More important, however, is the role of anti-diabetic agents, such as insulin, in promoting weight gain. It is therefore a vicious cycle…one that can only be appropriately addressed by targeting the weight problem.
Fighting Fat and Sugar
The strategy of weight reduction can be attacked from several angles. For one, lifestyle modification must be aggressively pursued. The CDC recommends 30 minutes of moderate physical activity most days of the week to maintain good health, 60 minutes to achieve significant weight loss. Meanwhile, diet high in cereal fiber and polyunsaturated fat and low in trans fat and glycemic load is considered low risk. Weight-reducing medications that assist patients in shedding fat, whether diabetic or not, are also already available in the market.
Whatever the approach, the message remains crystal clear: obesity is linked to type 2 diabetes, hence, measures to improve weight control must be adopted to reduce its incidence so that its economic impact can be lessened. In this light, diabetes and other chronic illnesses have been shown to be clearly preventable to some extent. It is for us, health professionals, patients, even lay people, to take action…and move.
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