Tuesday, March 04, 2008

Does obesity cause diabetes?

That obesity causes diabetes is almost a mantra. I think I see it claimed or implied at least once a day. See the article immediately below this one, for instance. So I decided to look at the evidence behind the claim. I looked at what appear to be the two most cited articles on the question -- by Seidell and by Mokdad et al..

Neither article goes any where near proving the claim. Seidell, in fact, notes the differing relationship between weight and diabetes in Asia versus the West and makes the entirely sensible observation that the two things are "common consequences of changing lifestyles" -- NOT directly linked, in other words. Both, for instance, could be a consequence of (say) reduced exercise.

And the Mokdad article is quite naive. It shows that fatties are more likely to have diabetes but again enables no causal inferences. Additionally, it does not allow for the curvilearity that is known to feature in relationships with obesity. In other words, it combines moderately overweight people with grossly overweight people -- which fies in the face of the fact that it is people of middling weight who live longest. It could be just the real fatties who tend to get diabetes at an accelerated rate.

And genetic effects are, of course, not mentioned anywhere, despite all we know (and have known for a long time) about the genetic influence on body weight. It could be that a genetic difference causes both diabetes AND a larger fat mass. So even severe dieting would not chase that pesky diabetes-causing gene away.

The fact that prevalence of diabetes has been increasing would seem at first to discount a genetic influence but it does not, of course. Many genetic influences need environmental "triggers" to become dominant and we just don't know what environmental triggers might have come to the fore in recent years. How about increased crime causing both stress and overeating as a response to stress? Who knows?

As far as I can see, then, the alleged effect of fat on diabetes is just a guess. Ho hum! Just another instance of crap medical "wisdom".

I wonder do pigs get diabetes? Fat pigs are a byword. And pigs are a pretty good animal model for human beings. Pig tissue is even used for direct implantation into human hearts! Rodent models always have dubious generalizability but I think I would believe a double-blind study with pigs.

So, you see, I am not like those (such as the Global Warmists) for whom no evidence will count. I have just specified precisely what evidence would convince me. And nor would the evidence concerned be hard to gather. You might even get some good bacon at the end of it! Yum!

Jungle frog’s anti-infection agent may help millions of diabetics

A nocturnal frog that dwells in the ponds and lagoons of the Amazon could prove to be an unlikely lifesaver for millions of people suffering from diabetes, researchers say. The South American “paradoxical frog” (Pseudis paradoxa) owes its name to an uncanny ability to shrink as it grows older. Scientists studying the properties of its slimy skin have found a substance that can stimulate the release of insulin, the vital hormone that is deficient in sufferers from diabetes.

Scientists have made an artificial copy of the peptide, a protein-building block that protects the frog from infection, and have suggested that it could be used to boost insulin production in people with Type 2 diabetes. In laboratory tests, researchers found that the paradoxical frog’s peptide, known as pseudin-2, increased release of insulin in cultured cells by 50 per cent. However, more work must be carried out before the therapy is ready to be tested on human patients.

Currently there are 2.3 million diagnosed sufferers from diabetes in the UK, most of whom have the Type 2 form of the disease. Usually occurring in middle age, Type 2 diabetes is strongly associated with lifestyle factors such as obesity and develops because the body does not produce enough insulin or becomes resistant to the concentrations available.

The joint team from the University of Ulster in Northern Ireland and United Arab Emirates University believe that a synthetic version of pseudin-2 could join a new class of medicines, called incretin mimetics, that help diabetics to control their condition when dietary changes or other medicines have failed.

The skin secretions of frogs and other amphibians are being investigated as a rich source of biological agents that may lead to new drugs. Byetta, a diabetes drug based on the saliva of an endangered lizard, the Gila monster of North America, is already available in the UK. But scientists believe that the frog’s secretions could be even more effective. Paradoxical frogs are one of the few animals whose young are bigger than their parents, with tadpoles growing up to 27cm (11in) in length while the mature frogs are only about 4cm long.

Yasser Abdel-Wahab, senior lecturer in biomedical sciences at the University of Ulster, said that the chemistry of amphibian peptides was very similar to that of some mammalian counterparts that help to regulate blood sugar. He studied samples from several different species of frog before finding the desired effect, he said. “We are at an exciting stage with this research,” he said. “We have tested a more potent synthetic version of the pseudin-2 peptide and have found that it has the potential for development into a compound for the treatment of Type 2 diabetes. Now we need to take this a step further and put our work into practice to try and help people with Type 2 diabetes. “More research is needed, but there is a growing body of work around natural anti-diabetic drug discovery that is already yielding fascinating results.” Further details of the research will be presented today at the Diabetes UK Annual Professional Conference in Glasgow.



Just some problems with the "Obesity" war:

1). It tries to impose behavior change on everybody -- when most of those targeted are not obese and hence have no reason to change their behaviour. It is a form of punishing the innocent and the guilty alike. (It is also typical of Leftist thinking: Scorning the individual and capable of dealing with large groups only).

2). The longevity research all leads to the conclusion that it is people of MIDDLING weight who live longest -- not slim people. So the "epidemic" of obesity is in fact largely an "epidemic" of living longer.

3). It is total calorie intake that makes you fat -- not where you get your calories. Policies that attack only the source of the calories (e.g. "junk food") without addressing total calorie intake are hence pissing into the wind. People involuntarily deprived of their preferred calorie intake from one source are highly likely to seek and find their calories elsewhere.

4). So-called junk food is perfectly nutritious. A big Mac meal comprises meat, bread, salad and potatoes -- which is a mainstream Western diet. If that is bad then we are all in big trouble.

5). Food warriors demonize salt and fat. But we need a daily salt intake to counter salt-loss through perspiration and the research shows that people on salt-restricted diets die SOONER. And Eskimos eat huge amounts of fat with no apparent ill-effects. And the average home-cooked roast dinner has LOTS of fat. Will we ban roast dinners?

6). The foods restricted are often no more calorific than those permitted -- such as milk and fruit-juice drinks.

7). Tendency to weight is mostly genetic and is therefore not readily susceptible to voluntary behaviour change.

8). And when are we going to ban cheese? Cheese is a concentrated calorie bomb and has lots of that wicked animal fat in it too. Wouldn't we all be better off without it? And what about butter and margarine? They are just about pure fat. Surely they should be treated as contraband in kids' lunchboxes! [/sarcasm].

9). And how odd it is that we never hear of the huge American study which showed that women who eat lots of veggies have an INCREASED risk of stomach cancer? So the official recommendation to eat five lots of veggies every day might just be creating lots of cancer for the future! It's as plausible (i.e. not very) as all the other dietary "wisdom" we read about fat etc.

10). And will "this generation of Western children be the first in history to lead shorter lives than their parents did"? This is another anti-fat scare that emanates from a much-cited editorial in a prominent medical journal that said so. Yet this editorial offered no statistical basis for its opinion -- an opinion that flies directly in the face of the available evidence.

Even statistical correlations far stronger than anything found in medical research may disappear if more data is used. A remarkable example from Sociology:
"The modern literature on hate crimes began with a remarkable 1933 book by Arthur Raper titled The Tragedy of Lynching. Raper assembled data on the number of lynchings each year in the South and on the price of an acre's yield of cotton. He calculated the correlation coefficient between the two series at -0.532. In other words, when the economy was doing well, the number of lynchings was lower.... In 2001, Donald Green, Laurence McFalls, and Jennifer Smith published a paper that demolished the alleged connection between economic conditions and lynchings in Raper's data. Raper had the misfortune of stopping his analysis in 1929. After the Great Depression hit, the price of cotton plummeted and economic conditions deteriorated, yet lynchings continued to fall. The correlation disappeared altogether when more years of data were added."
So we must be sure to base our conclusions on ALL the data. But in medical research, data selectivity and the "overlooking" of discordant research findings is epidemic.

"What we should be doing is monitoring children from birth so we can detect any deviations from the norm at an early stage and action can be taken". Who said that? Joe Stalin? Adolf Hitler? Orwell's "Big Brother"? The Spanish Inquisition? Generalissimo Francisco Franco Bahamonde? None of those. It was Dr Colin Waine, chairman of Britain's National Obesity Forum. What a fine fellow!


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