Salivary matrix metalloproteinase (MMP-8) levels and gelatinase (MMP-9) activities in patients with type 2 diabetes mellitus

We studied the salivary levels and activities of the matrix metalloproteinases (MMP)-8 and -9 in 45 type 2 diabetic patients and 77 control subjects. The patients' mean glycosylated haemoglobin (HbA(1c)) was 8.7%, indicating an unsatisfactory metabolic control of the disease. The MMP levels were further related to the clinical and microbiological periodontal findings as well as to salivary flow rate and other factors. The salivary flow rate, albumin and amylase concentrations were similar in type 2 diabetic patients to those in the control group. The mean gingival and periodontal pocket indexes were higher in the diabetes group. The number of potential periodontopathogenic bacteria was lower, however, in the diabetic than in the control group. Zymography and immunoblotting revealed that the major MMPs in the type 2 diabetic patients' saliva were MMP-8 and MMP-9. Salivary MMP levels and activities in type 2 diabetic patients were in general similar to those in the control group. However, the correlation coefficients using multiple regression analysis revealed that gingival bleeding, pocket depths and HbA(1c), were associated with increased MMP-8 levels which, in turn, were negatively predicted by elevated plasma lipid peroxide levels in the diabetic group. Our data on salivary MMP-8 and -9 do not support the concept of generalized neutrophil dysfunction in unbalanced diabetes. Moreover, plasma lipid peroxidation levels reflecting the increased oxidative burden, which is generated mainly by triggered neutrophils, do not indicate neutrophil dysfunction due to diabetes, but may rather be related to the increased tissue damage in an uncontrolled disease. However, advanced periodontitis in type 2 diabetes seems to be related to elevated salivary MMP-8 levels which might be useful in monitoring periodontal disease in diabetes.