Background : A high incidence of periodontal disease has been reported among diabetics, however the role of saliva in the occurrence of this oral disease in these patients is yet to be understood. Objective: To determine the effects of type-2 diabetes and periodontal disease on salivary flow rate and biochemical composition. Design: A prospective study involving 40 adult human subjects divided equally into four groups of diabetics with periodontitis (group 1), diabetics without periodontitis (group 2), non diabetics with periodontitis (group 3) and non diabetics without periodontitis (group 4). Methodology: Saliva samples were collected and analyzed for salivary glucose, total protein, calcium, sodium, potassium, chloride and bicarbonate. Salivary flow rates were also determined. Results: Salivary glucose and potassium levels were significantly higher (P = 0.002 and 0.04 respectively) in diabetic patients regardless of periodontal disease (mean = 100.7 ± 9.33 mg/dl; 111.5 ± 32.85 mg/dl and 23.79 ± 5.19 mg/dl; 22.9 ± 6.25 mg/dl respectively) compared with non diabetic participants (mean = 80.5 ± 30.85 mg/dl; 62.5 ± 31.89 mg/dl and 19.23 ± 5.04 mg/dl; 17.74 ± 4.68 mg/dl respectively). In contrast, there was no significant difference in saliva flow rates and levels of total protein, Na+, Ca++, Cl- and HCO3- between the groups. Conclusion: Salivary glucose and potassium levels were significantly higher among diabetics with or without periodontitis compared with non-diabetics with or without periodontitis. However, biochemical composition of saliva in diabetic individuals has probably little role in their susceptibility to periodontitis.