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

Abstract

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/m(2)) 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.