Complex sentence: There has been long history of dietary treatment of diabetes mellitus--dietary treatment of diabetes mellitus was used in Egypt since 3,500 B.C., and was used in India by Sushruta and Charaka more than 2000 years ago.
Split into simpler sentences: There has been long history of dietary treatment of diabetes mellitus. Dietary treatment of diabetes mellitus was used in Egypt since 3,500 B.C. and was used in India by Sushruta and Charaka more than 2000 years ago.