Porphyromonas gingivalis infection is associated with carotid atherosclerosis in non-obese Japanese type 2 diabetic patients

The aim of the present study was to investigate whether non-obese Japanese type 2 diabetic patients with porphyromonas gingivalis infection have atherosclerotic vascular diseases. A total of 134 non-obese Japanese type 2 diabetic patients (96 men and 38 women, aged 36 to 84 years, body mass index [BMI] 20.1 to 26.9 kg/m²) were studied. In conjunction with BMI, glycosylated hemoglobin (HbA_1c), fasting glucose, and serum lipids (triglycerides, total cholesterol, high-density lipoprotein [HDL] cholesterol, low-density lipoprotein [LDL] cholesterol) were measured. LDL cholesterol was calculated using the Friedewald formula. Using high-resolution B-mode ultrasound scan, we measured intimal medial thickness (IMT) in plaque-free segments of bilateral common carotid arteries, and the mean of IMT in 2 vessels was used for the analysis. Furthermore, we calculated the degree of stenosis in plaque segments of bilateral common carotid arteries. The degree of carotid atherosclerosis was expressed as a percentage ratio between the area of plaque and that of the lumen using the formula (Lumen Area Residual - Lumen Area)/Lumem Area x 100. Both the areas were automatically measured by the system on a frozen transverse scanning plane at the site of maximal narrowing. When 2 or more plaques were present in the vessel, only that causing the greatest degree of stenosis was considered for analysis. Values represent mean±SEM unless otherwise stated. Immunoglobulin G (IgG) titer against porphyromonas gingivalis was 245 ± 65 (mean ± 2 SD) in nondiabetic healthy subjects. In contrast, there was a wide variation in IgG titer against porphyromonas gingivalis in type 2 diabetic patients studied (range, 16 to 26,800). Thus, we classified our type 2 diabetic patients into 2 subpopulations according to the value of mean ± 2 SD (= 310) of nondiabetic healthy subjects: one with high IgG titer against porphyromonas gingivalis (>310) (1,422 ± 408) and the other with normal IgG titer against porphyromonas gingivalis (<310) (152 ± 10, P = .002). The populations did not differ with respect to age, sex, BMI, fasting glucose, HbA_1c, serum triglycerides, total, HDL, and LDL cholesterol levels. Although the mean IMT in plaque-free segments was not different between the 2 groups (0.73 ± 0.03 v 0.68 ± 0.02 mm, P = .098), the degree of stenosis in plaque segments was significantly higher in the high IgG titer group (12.0% ± 2.2%) than in normal one (5.5% ± 1.4%, P = .009). From these results, it can be concluded that porphyromonas gingivalis infection, although still a subclinical infection, is associated with atherosclerotic vascular disease in non-obese Japanese type 2 diabetic patients.