A pilot study on glycemia and insulin resistance in patients with severe periodontitis

Comparison of Absolute and Relative Grip Strength to Predict Incidence of Diabetes Mellitus in Korea: A Prospective Cohort Study

Background: This study aimed to investigate the association between absolute grip strength (AGS), relative grip strength (RGS) levels, and the risk of developing diabetes in middle-aged adults, utilizing longitudinal data. Methods: A total of 1935 participants, 51-81 years of age, were engaged in surveys both in 2017-2018 and during the subsequent follow-up survey in 2019-2020. Diabetes diagnosis and treatment were the criteria for categorizing individuals as "diabetic." Grip strength was measured using the JAMA-5030J1 equipment (SAEHAN, Korea), and AGS and RGS were also categorized into tertiles by gender. A proportional hazards Cox regression model was used to evaluate the relationship among AGS, RGS, and the risk of developing diabetes. Subsequently, we computed the hazard ratio (HR) and 95% confidence interval (95% CI) for the risk of developing diabetes. Results: After adjusting for various confounding variables, a significant reduction in diabetes risk was observed in the high grip strength group, adjusted for body mass index (RGS1) and body weight (RGS2), compared with the low RGS1 and RGS2 groups (RGS1 HR = 0.54, 95% CI = 0.36-0.80; RGS2 HR = 0.50, 95% CI = 0.34-0.73). However, there were no significant associations between AGS and diabetes risk. Furthermore, significant differences in the relationship among AGS, RGS levels, and the risk of developing diabetes were found across gender and insulin resistance levels. Conclusion: This study underscores the importance of RGS levels in predicting the incidence of diabetes, with AGS, RGS1, and RGS2 emerging as significant predictive indicators for assessing diabetes risk.

Chronic periodontitis induces the proliferation of pancreatic β-cells to cause hyperinsulinemia in a rat model

BACKGROUND AND OBJECTIVE

The purpose of this study was to determine if chronic periodontitis (CP) may induce hyperinsulinemia and may have the effect of on pancreatic β-cell proliferation in a rat model.

MATERIALS AND METHODS

Twelve male Sprague-Dawley rats were divided into two groups: the CP group and the control group (Con group). The following contents were evaluated: pathological changes in periodontal soft and hard tissues; serum lipopolysaccharide (LPS) level, serum fasting insulin (FINS) level, fasting blood glucose (FBG) level, and homeostasis model assessment (HOMA) β (HOMA-β) index; histopathological examination of islets; immunohistochemistry of insulin and p-Smad2 expression in islets; immunofluorescence of changes in the relative number of β-cells and the number of Ki67-positive β-cells. Western blotting was used to analyze p-Smad2/Smad2 levels. Results were analyzed by two independent samples t tests.

RESULTS

Increased serum LPS level, FINS level, and HOMA-β index were observed in the rats of the CP group; FBG level did not change significantly; histological assessments showed an enlarged islet area, increased insulin content, relatively increased β-cells, increased Ki67-positive β-cells, and decreased p-Smad2 expression in islets in the rats of the CP group.

CONCLUSION

Our study results link CP-induced hyperinsulinemia with changes in islets, such as islet hyperplasia and compensatory β-cell proliferation, by using a CP rat model.

Association between Periodontitis and HbA1c Levels in Non-Diabetic Patients: A Systematic Review and Meta-Analysis

BACKGROUND

A high detection rate of diabetes among dental visitors has been reported recently. This systematic review aimed to evaluate the association between periodontitis and glycated hemoglobin (HbA1c) levels among non-diabetic individuals.

METHODS

The EMBASE, MEDLINE, Web of Science, Cochrane Library, PubMed, and Open GREY databases were searched, and observational studies published until 1st June 2023 were identified. A methodological quality assessment was conducted based on the original and modified versions of the Newcastle-Ottawa scale. Cohort, case-control, and cross-sectional studies that performed clinical periodontal examinations and measured HbA1c levels in non-diabetic adults were included. A meta-analysis was conducted to estimate the weighted mean difference (WMD) between individuals with and without periodontitis.

RESULTS

In total, 29 case-control and 5 cross-sectional studies were selected from 2583 potentially eligible articles. Among them, sixteen case-control and three cross-sectional studies with moderate to high quality were selected for the meta-analyses. The HbA1c levels in periodontitis patients were significantly higher than those in individuals with healthy periodontal conditions (WMD = 0.16; p < 0.001) among the non-diabetic populations.

CONCLUSIONS

This study reveals a significant association between periodontitis and HbA1c levels in non-diabetic populations. Thus, HbA1c screening may be recommended to detect potential hyperglycemia in non-diabetic periodontitis patients.

Diabetes mellitus promotes susceptibility to periodontitis-novel insight into the molecular mechanisms

Diabetes mellitus is a main risk factor for periodontitis, but until now, the underlying molecular mechanisms remain unclear. Diabetes can increase the pathogenicity of the periodontal microbiota and the inflammatory/host immune response of the periodontium. Hyperglycemia induces reactive oxygen species (ROS) production and enhances oxidative stress (OS), exacerbating periodontal tissue destruction. Furthermore, the alveolar bone resorption damage and the epigenetic changes in periodontal tissue induced by diabetes may also contribute to periodontitis. We will review the latest clinical data on the evidence of diabetes promoting the susceptibility of periodontitis from epidemiological, molecular mechanistic, and potential therapeutic targets and discuss the possible molecular mechanistic targets, focusing in particular on novel data on inflammatory/host immune response and OS. Understanding the intertwined pathogenesis of diabetes mellitus and periodontitis can explain the cross-interference between endocrine metabolic and inflammatory diseases better, provide a theoretical basis for new systemic holistic treatment, and promote interprofessional collaboration between endocrine physicians and dentists.

Periodontitis as a promoting factor of T2D: current evidence and mechanisms

Periodontitis is an infectious disease caused by an imbalance between the local microbiota and host immune response. Epidemiologically, periodontitis is closely related to the occurrence, development, and poor prognosis of T2D and is recognized as a potential risk factor for T2D. In recent years, increasing attention has been given to the role of the virulence factors produced by disorders of the subgingival microbiota in the pathological mechanism of T2D, including islet β-cell dysfunction and insulin resistance (IR). However, the related mechanisms have not been well summarized. This review highlights periodontitis-derived virulence factors, reviews how these stimuli directly or indirectly regulate islet β-cell dysfunction. The mechanisms by which IR is induced in insulin-targeting tissues (the liver, visceral adipose tissue, and skeletal muscle) are explained, clarifying the influence of periodontitis on the occurrence and development of T2D. In addition, the positive effects of periodontal therapy on T2D are overviewed. Finally, the limitations and prospects of the current research are discussed. In summary, periodontitis is worthy of attention as a promoting factor of T2D. Understanding on the effect of disseminated periodontitis-derived virulence factors on the T2D-related tissues and cells may provide new treatment options for reducing the risk of T2D associated with periodontitis.

The Presence of Periodontitis Exacerbates Non-Alcoholic Fatty Liver Disease via Sphingolipid Metabolism-Associated Insulin Resistance and Hepatic Inflammation in Mice with Metabolic Syndrome

Clinical studies have shown that periodontitis is associated with non-alcoholic fatty liver disease (NAFLD). However, it remains unclear if periodontitis contributes to the progression of NAFLD. In this study, we generated a mouse model with high-fat diet (HFD)-induced metabolic syndrome (MetS) and NAFLD and oral P. gingivalis inoculation-induced periodontitis. Results showed that the presence of periodontitis increased insulin resistance and hepatic inflammation and exacerbated the progression of NAFLD. To determine the role of sphingolipid metabolism in the association between NAFLD and periodontitis, we also treated mice with imipramine, an inhibitor of acid sphingomyelinase (ASMase), and demonstrated that imipramine treatment significantly alleviated insulin resistance and hepatic inflammation, and improved NAFLD. Studies performed in vitro showed that lipopolysaccharide (LPS) and palmitic acid (PA), a major saturated fatty acid associated with MetS and NAFLD, synergistically increased the production of ceramide, a bioactive sphingolipid involved in NAFLD progression in macrophages but imipramine effectively reversed the ceramide production stimulated by LPS and PA. Taken together, this study showed for the first time that the presence of periodontitis contributed to the progression of NAFLD, likely due to alterations in sphingolipid metabolism that led to exacerbated insulin resistance and hepatic inflammation. This study also showed that targeting ASMase with imipramine improves NAFLD by reducing insulin resistance and hepatic inflammation.

[Advances in Research on the Mechanism of Association Between Periodontitis and Diabetes Mellitus]

Periodontitis and diabetes mellitus are both chronic diseases with a rather high prevalence and they are closely associated with each other. On one hand, diabetes mellitus poses as a risk factor for periodontitis. On the other hand, periodontitis has a negative impact on glucose control in diabetic patients. The two-way relationship has aroused a lot of research interest in recent years. Herein, approaching the issue by looking at the effect of periodontitis on diabetes, we summarized the mechanism of the traditional periodontal pocket-blood circulation pathway and reviewed the role of the oral-gut axis in the mechanism, which has been proposed in recent years. In addition, regarding the impact of diabetes on periodontitis, we summarized new findings concerning changes in oral microbiota, abnormal levels of cytokines and adipokines, oxidative stress, unbalanced osteogenic and osteoclastic activities, and the accumulation of advanced glycation end-products. We hope this paper will be helpful for further studies on the mechanism of association between periodontitis and diabetes.

Comparison of the triglyceride glucose (TyG) index, triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio, and metabolic score for insulin resistance (METS-IR) associated with periodontitis in Korean adults

Background:

Periodontitis is one of the most common diseases associated with the oral cavity. Previous studies have suggested that there is an association between periodontitis and metabolic dysfunction. Recently, the triglyceride glucose (TyG) index, high-density lipoprotein cholesterol (TG/HDL-C) ratio, and metabolic score for insulin resistance (METS-IR) index have been identified as useful markers for assessing insulin resistance.

Objective:

This study aimed to evaluate the relationship between periodontitis and non-insulin-based insulin resistance (IR) indices and compare the predictive values of these indices in the Korean population.

Design:

This is a cross-sectional study.

Methods:

A total of 13,584 participants were included in the 2013–2015 Korean National Health and Nutrition Examination Survey data. A community periodontal index score⩾3 was used to define periodontitis. Participants were divided into quartiles according to each index. Odds ratios (ORs) and 95% confidence intervals (CIs) for the prevalence of periodontitis and the TyG index, TG/HDL-C ratio, and METS-IR index quartiles were calculated using multiple logistic regression analysis. We estimated the areas under the receiver operating characteristic curves (AUCs) of the indices to compare the predictive values of the three indices.

Results:

Compared with quartile 1, the fourth quartile ORs (95% CIs) for periodontitis were 1.23 (1.01–1.49) for the TyG index, 1.23 (1.02–1.48) for the TG/HDL-C ratio, and 1.53 (1.25–1.88) for the METS-IR index after adjustment for confounders. The AUC (95% CIs) was 0.608 (0.598–0.618) for the TyG index, 0.600 (0.590–0.610) for the TG/HDL-C ratio, and 0.617 (0.608–0.627) for the METS-IR index to identify periodontitis. The predictive power of METS-IR was significantly higher than that of the TyG index and TG/HDL-C.

Conclusion:

Higher TG/HDL-C ratio, TyG, and METS-IR indices are associated with a higher prevalence of periodontitis. The METS-IR index is a more powerful predictor of periodontitis prevalence than the TyG index and TG/HDL-C ratio.