A common herpes virus might trigger an unusual form of type 2 diabetes found in sub-Saharan Africa that is characterized by rapid onset of disease, French researchers said on Tuesday.

Over the past 20 years this atypical form has emerged as one of the most frequent in populations of African origin. A link to the herpes virus is a step toward identifying a possible drug target, the researchers said.

People who have the unusual form of type 2 diabetes need insulin injections right away until the condition stabilizes, said Jean-Francois Gautier, an endocrinologist at the Hopital Saint-Louis in Paris, who led the study.

"We are looking for something that could explain why these people start the disease so acutely like people with type 1 diabetes," he said. "We think this virus may convert the type 2 diabetes into an atypical form."

Type 2 diabetes -- increasing rapidly worldwide -- is the most common form of the disease and is closely linked to obesity and physical inactivity. Type 1 diabetes is an autoimmune disease often diagnosed at an early age.

Uncontrolled diabetes can result in a wide variety of serious health complications including heart disease, stroke, vision loss, amputation and kidney disease.

Knowing a person will only need insulin for just a few weeks after diabetes sets in -- as in the case of the atypical form -- can help doctors manage limited insulin supplies in parts of Africa, Gautier added in a telephone interview.

"It is important to know that in some cases you can stop insulin therapy after a few weeks," he added.

In sub-Saharan Africa about 20 percent of people with diabetes have the atypical form of type 2 diabetes, which the researchers linked to the human herpesvirus 8, Gautier said. They published their findings in the Journal of the American Medical Association.

Their study of more than 200 recent African immigrants to France found that about 90 percent of the 81 people who had the atypical form of the disease had antibodies in their blood against the herpes virus compared to 50 percent of healthy people.

The actual herpes virus was also in the blood of half the people with the uncommon form of diabetes during the first few weeks but not in any of the volunteers who had classical type 2 diabetes, the researchers said.

As a final piece of evidence, they cultivated cells taken from the pancreas of a corpse and found that the virus was able to infect the cells that normally secrete insulin, Gautier said.

(Editing by Will Dunham)