* Novo Nordisk says U.S. market has not changed recently

* U.S. challenge is Sanofi's not market's - analyst

* Novo more cautious on Tresiba U.S. launch date

* Shares up almost 4 percent (Adds analysts, details on Tresiba, updates shares)

By Teis Jensen and Sabina Zawadzki

COPENHAGEN, Oct 30 (Reuters) - Novo Nordisk reassured investors that its diabetes drugs business in the United States would continue to grow, after French rival Sanofi warned that price competition would hamper its U.S. sales.

The Danish insulin manufacturer said it expected high single-digit sales growth in its global business next year and a 10 percent rise in operating profit, after posting third-quarter results more or less in line with analysts' expectations.

Shares in Sanofi plunged on Tuesday after its comments on the U.S. market, and then fell even further after the messy ouster of its chief executive a day later.

Novo Nordisk said it had been warning for a while about price competition in the world's largest diabetes market. On Thursday it said rebates on drugs -- which manufacturers such as Novo pay to get supply contracts -- will be higher next year.

"There's no real change in the pricing environment. There's always been competitive pressure in the United States," Chief Financial Officer Jesper Brandgaard told a conference call.

"We're also looking at a market where the current market leader (Sanofi's) glargine is getting closer to patent expiry with the opportunity that our similar offering can have for the purchasers of drugs," he said.

Novo had "reasonable visibility" for 2015, he said, as it had already concluded deals with pharmacy benefit managers, who administer prescription drug benefits within insurance plans, to get its drugs on their lists.

Analysts said Novo Nordisk's position in the United States appeared safer as it had paid higher rebates while Sanofi would struggle with its legacy position of dominance when the glargine drug, branded Lantus, runs off patent.

"Sanofi have simply not given enough discounts considering how much they raised prices and they will need to find another level launching Toujeo in 2015," Sydbank analyst Soren Hansen said, referring to Lantus' successor drug.

"Despite indicating a market problem on Tuesday, the trend described by Sanofi is mainly its own problem," he said.

Either way the drugmakers, together with U.S. competitor Eli Lilly, will have to get used to an era of lower prices, analysts said.

TRESIBA

"With Novo poised to launch its second-generation basal insulin Tresiba in the United States in 2016 or 2017 and Lilly readying its biosimilar in 2016, wringing out price increases after next year will be all but impossible," Evaluate Pharma, an industry newsletter, said.

Novo Nordisk's big hope for the future is Tresiba, which the U.S. Food & Drug Administration (FDA) refused to approve in February last year, demanding more tests. The unexpected decision was a big blow to the company and its shares plummeted.

On Thursday, it presented a more cautious assessment of when it would submit more data to the FDA and subsequently launch the drug.

Novo also gave no concrete guidance on when it expected an FDA decision on its Saxenda drug, used to treat obesity.

Analysts had said they were not too concerned when an informal deadline for the FDA to approve or reject the drug passed on Oct. 20.

Shares in Novo Nordisk rose almost 4 percent, outperforming a 0.08 dip in the Danish benchmark index.

Novo's 2015 guidance reflects comments made by Novo Nordisk's deputy chief executive, Kaare Schultz, that the company would increase revenues by about 10 percent every year for the next 10 years.

"Novo delivered in-line numbers and importantly reassured with respect to preliminary, full-year 2015 guidance," Citi Research said in a note to clients.

Operating profit for the third quarter rose to 8.57 billion Danish crowns ($1.45 billion), slightly above an average forecast of 8.47 billion crowns in a Reuters poll of analysts. .

Novo narrowed its 2014 sales guidance in local currencies to growth of between 7 and 9 percent from an earlier expected 7 to 10 percent.

Operating profit is still seen growing around 10 percent this year in local currencies. Operating profit growth measured in Danish crowns is now seen 3 percentage points lower than when measured in local currencies, from an earlier 5 percentage points lower. ($1 = 5.9095 Danish crown) (Additional reporting by Annabella Nielsen; Editing by Sabina Zawadzki/Crispian Balmer/Susan Fenton)