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1228 VOLUME 9 | NUMBER 10 | OCTOBER 2003 NATURE MEDICINE

Mexican shamans have a wealth of experiencein treating ‘sweet blood’, a disease that affectsthe indigenous population in the highlands ofMexico at record rates. Their wisdom is nowhelping researchers develop diabetes drugsfrom natural remedies.

According to a new report released at theEighteenth World Congress of theInternational Diabetes Federation in Paris, 194million people worldwide are diabetic. Thenumbers are expected to rise to 333 million by2025. The prevalence of diabetes is particularlyhigh among some native communities.

Nearly one in three Native Americans aged55 or older has diabetes, according to new datafrom the US Centers for Disease Control andPrevention. The data also indicate that theprevalence of type 2 diabetes among nativecommunities is growing faster than in theoverall US population.

The prevalence of type 2 diabetes has tradi-tionally been high in the highlands of Mexico.Helmut Wiedenfeld, a pharmacologist at theUniversity of Bonn, and his colleagues investi-gated the plant extracts shamans give their dia-betic patients.

“We have now finished the phytochemicalanalysis of four plants, and we know theiractive ingredients,” says Wiedenfeld. Theresearchers presented the latest findings—thediscovery of new pyron-glycosides derivedfrom the plant Acosmium panamense—inearly September at the annual meeting of theSociety for Medicinal Plant Research in Kiel,Germany.

Preliminary experiments in rat models ofdiabetes confirm that the plant extracts, as wellas mixtures of their active ingredients, have ahypoglycemic effect. Small clinical trials arenow under way in Mexico City. Wiedenfeld isalso trying to get a pharmaceutical company todevelop herbal prescription drugs for type 2diabetes.

Because the studies are preliminary, cau-tions Edmond Ryan at the University ofAlberta in Canada, it is too early to predict thefate of these treatment candidates. “I thinkthere are a lot of good chemicals out there innature that will be beneficial,” Ryan says. “Butproving that they are beneficial in good clini-cal trials is the most critical thing.”

A second, more promising, approach isbased on Western medicine and uses a com-pound from the saliva and venom of the lizardHeloderma suspectum, which lives in the Gilariver valley in Arizona. The valley is home toPima Indians, who have the highest preva-lence of diabetes in the world.

When the Gila monster lizard bites down onits prey, it secretes the chemical exendin-4,which is homologous to, and acts like humanglucagon-like peptide-1 (GLP-1). Exendin-4increases insulin secretion in a glucose-depend-ent fashion, which means that the risk forhypoglycemia is low. “It is like a self-regulatedsmart drug,” says Alain Baron, senior vice-pres-ident of clinical research at AmylinPharmaceuticals, which is developing the drug.

The compound has many other properties

that make it attractive for the treatment of dia-betes. For example, new research suggests thatit may be capable of correcting the β-cell deficitin diabetes. But unlike its cousin, GLP-1,exendin-4 has a long half-life and is thereforeabout 100 to 1,000 times more potent.

Exendin-4 is currently being tested in threerandomized, placebo-controlled phase 3 trialsin type 2 diabetes patients who are taking met-formin, a sulfonylurea, or both, but are notachieving glucose control. Results are expectedlater this year. At the Paris meeting, Baron pre-sented preliminary results suggesting that after24 weeks of treatment, 44% of patientsachieved glucose levels that were within theAmerican Diabetes Association’s target range.

“These human results are very encourag-ing,” says Timothy Kieffer at the University ofBritish Columbia in Canada. “They continueto support the notion that so-called GLP-1mimetics will offer patients with diabetes fan-tastic new treatment options.”

The company aims to gain approval fromthe US Food and Drug Administration by2005, but questions remain. For example, nau-sea may lower treatment compliance. It is alsointriguing that lizard venom would treat dia-betes, notes Kieffer. “One wonders what thefunction of this peptide is in the Gila monstervenom,”he says.“Clearly its bite is not designedto treat diabetes.”

Martina Habeck, London

Diabetes treatments get sweet help from nature

Some new diabetes treatments are being derivedfrom plants in the Mexican highlands.

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Canada considering a ‘CDC North’A new national public health center might bein Canada’s future, says Federal HealthMinister Anne McLellan. The center, whichwould be similar to the US Centers for DiseaseControl and Prevention, would be “a nervecenter of expertise and research,” McLellanannounced in her 18 August speech at theCanadian Medical Association’s annual meet-ing.

Canada’s health-care system was left reelingafter the epidemic of severe acute respiratorysyndrome (SARS) there earlier this year. Itbecame obvious then that Canada lacksexpertise in dealing with public health crises,says Alison McGeer, a leading SARS researcherand director of infection control at MountSinai Hospital in Toronto. “What we mostmissed was a team to collect and analyze datamore quickly as the outbreak was going on,”McGeer says. In the case of another outbreak,the proposed national agency would coordi-

nate epidemiology, laboratory investigationand public health experts across the country.

The center is just one part of a pledge byCanada’s federal, provincial and territorialhealth ministers to make public health theirtop priority. The ministers are also working toincrease public health human resources, forma national health council to monitor health-care reform and spending, enhance existingnational disease surveillance and informationinfrastructure and make the case for an addi-tional C$2 billion for health care.

The details of the center’s structure andlocation are still being worked out by healthministers. But it won’t come cheap—costs forthe multisite agency are estimated to approachC$1 billion. “Getting money for public healthis always a problem,” says McGeer. “[But] Ihope we’ve learned enough from SARS inCanada that we’ll spend the money.”

Pierrette Lo, New York

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