May 3 (Reuters) - U.S.-German genetic testing company Qiagen NV reported slightly better-than-expected quarterly earnings on Monday as sales growth in its non-coronavirus products added to high demand for COVID-19 tests.

Qiagen's products include several types of COVID-19 tests that helped it to boost sales over the past year and recover from a difficult 2019 that included profit warnings, a slump in China business and a CEO departure.

The company said it plans to keep growing sales even after the pandemic by broadening its portfolio and making sure each coronavirus-related test has other applications as well.

"We have made multiple product expansions to our non-COVID related portfolio, including the launch of a Lyme disease test," Qiagen's Chief Executive Thierry Bernard said in a statement.

The company said first-quarter adjusted earnings rose to 65 cents per share on a currency-adjusted basis, beating the 63 cents on average forecast by analysts in a Vara Research poll, as research laboratories around the world have returned to work and clinical labs moved beyond COVID-19 testing.

"This performance was particularly driven by 16% constant currency growth in sales of non-COVID product groups that represented 64% of our sales," Bernard said.

Qiagen also confirmed its 2021 forecast for adjusted earnings of $2.42 to $2.46 per share and net sales growth of 18% to 20% at constant exchange rates. ($1 = 0.8262 euros) (Reporting by Zuzanna Szymanska in Gdansk; Editing by Bill Berkrot)