The study gives a more accurate figure for the number of deaths from the drug, known by the lab name as benfluorex, which had previously been put at between 1,000 and 2,000.
Its French manufacturer, Servier, is being probed on suspicion of dishonest practices and deception.
Mahmoud Sureik of Inserm, who co-led the investigation into the drug, estimates 3,100 people had required hospitilisation during the 33 years the drug was sold.
In 2009, the drug was pulled from the European market amid evidence that it damaged heart valves and caused pulmonary hypertension. The figures for the deaths are based on those from faulty heart valves, and not from hypertension, among major users of the drug.
According to Servier, 145 million packets of Mediator were sold on the French market before it was pulled.
Mediator was initially licensed as a way of reducing levels of fatty proteins, lipids, with the claim that it helped diabetics control their blood sugar level. But it also suppressed the appetite which meant it gained a second official use to help obese diabetics lose weight.
The Mediator case came to light after a scandal involving a similar type of anti-obesity drug, fenfluramine, in the late 1990s.