Objective The aim of this study was to investigate the association between periodontitis and total serum cholesterol level in patients with type 2 diabetic nephropathy (T2DN). Background Periodontitis is now recognized as the sixth complication of diabetes and can also affect other complications of diabetes, including nephropathy and coronary artery diseases. Studies have considered dyslipidemia as a risk factor for exacerbation of periodontitis. Methods A total of 119 T2DN patients with chronic periodontitis were included in this observational study. Participants were stratified into the Normal (serum total cholesterol <5.17 mmol/L, n = 89) and the Dyslipidemia groups (serum total cholesterol >= 5.17 mmol/L, n = 30). Participants completed a validated questionnaire that collected information on oral hygiene behaviors and knowledge of oral health and underwent a clinical oral examination. The number of remaining teeth, probing depth (PD), clinical attachment level (CAL), and bleeding index (BI) was recorded. Physical examination and laboratory tests (fasting plasma glucose, serum glycosylated hemoglobin (HbA1c), total cholesterol, high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), triglyceride, and high-sensitivity C-reactive protein levels) were performed. Results Means of CAL and BI were significantly higher in the Dyslipidemia group compared with the Normal group. In the Dyslipidemia group, PD and percent of sites with PD >= 4 mm were positively correlated with urinary albumin/creatinine ratios; PD and percent of sites with PD >= 4 and PD >= 5 mm were positively correlated with HbA1c level; a number of remaining teeth were negatively correlated with serum LDL-C level. After adjusting for age, gender, body mass index, smoking, FPG, and serum HbA1c and triglyceride levels, BI was found to be positively associated with dyslipidemia in T2DN patients with periodontitis. Conclusion T2DN patients with chronic periodontitis had a 2.355-fold higher risk of developing dyslipidemia, implying an important relationship between periodontitis and blood lipid control among T2DN patients.