Sun Pharmaceutical Industries has entered into a deal to market Merck & Co's diabetes drugs - sitagliptin and sitagliptin plus metformin  - in India, the two drugmakers said in a statement on Monday. Under the deal, Sun will have the rights to market the drugs only in India under different brand names, the firms said. Earlier in April, Sun and Merck formed a joint venture to develop and manufacture generic drugs for emerging markets.