GlaxoSmithKline NYSE: GSK) believes that GLP-1 diabetes drugs, including its albiglutide experimental compound and Novo Nordisk A/S’s Victoza, are unlikely to win clearance to treat obesity because of effectiveness questions.

“Frankly as a class, I don’t think GLP-1s would make it as obesity medicines,” Moncef Slaoui, Glaxo’s chairman of research and development, said in an interview Wednesday in London. “Even with Victoza, personally, I would not” consider it for obesity.

Glaxo, which is based in London, plans early next year to seek regulatory approval for albiglutide, a form of a hormone called GLP-1 that stimulates the pancreas to produce more insulin, as a once-weekly diabetes treatment.

Bagsvaerd, Denmark-based Novo is studying Victoza, already on the market to treat Type 2 diabetes, as a potential weight-loss medicine.

Novo said in June that patients taking Victoza lost 3.9 kilograms (8.6 pounds) on average, compared with 2.9 kilograms for those taking a competing drug.

The limited weight loss, the difficulty of sustaining results and potential side effects “would be a challenge for that medicine to be approved for obesity use,” Slaoui said.

Novo Nordisk is the world’s biggest insulin maker. Victoza, a once-daily GLP-1 drug, generated sales of $1.1 billion last year.

The company operates a large manufacturing plant in Clayton, N.C.

GSK operates its North American headquarters in RTP.

[GSK ARCHIVE: Check out 10 years of GSK stories as reported in WRAL Tech Wire.]