A comparative study of Oral Microflora of Normal, Non-Diabetic and Diabetic Periodontitis Patients was carried out.  It resulted in Microflora common in all types were gram positive facultative rods and cocci. In Normal patients Gram positive facultative anaerobic, fermenting cocci were predominant where as in Non -Diabetic with Periodontitis patient showed growth of microbiota that are gram negative and positive, capnophilic, motile and anaerobic rods and cocci belonging to members of genera Streptococcus and Actinomyces. But in patients with Diabetic and Periodontitis there were subsequent increase in Gram negative, obligate anaerobic, proteolytic, motile bacterial species. Numerous oral changes were seen in diabetic patients including alterations in the flora of oral cavity, greater predominance of Candida albicans, Hemolytic Streptococci and Staphylococcus. Total bacterial loads were more in Diabetic Periodontitis Patients than the microflora in Non- Diabetic with Periodontitis patients. Diabetes increases the risk and severity of periodontal diseases. Number and proportion of different periodontal pathogens were more in patients with Diabetes and Periodontitis. In Diabetic Periodontitis Patient, Periodontal therapy may have beneficial effects on glycemic control.