Association Between Diabetic Retinopathy and Periodontitis-A Systematic Review

Association between periodontal disease and systemic diseases: a cross-sectional analysis of current evidence

BACKGROUND

Numerous systematic reviews and meta-analyses have been published that evaluate the association between periodontal disease and systemic diseases, many of which address similar topics. Moreover, their quality requires assessment. Therefore, we performed a cross-sectional analysis to examine the evidence on the relationship between periodontal disease and systemic diseases.

METHODS

The PubMed, Embase, Web of Science, and the Cochrane Library databases were systematically searched to identify relevant systematic reviews and meta-analyses. Only studies that considered periodontal disease as the exposure factor and various systemic diseases as the outcome were included. The basic characteristics and pertinent data from the selected studies were extracted. The modified version of A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2) was employed for quality assessment, while R software was used for statistical analysis.

RESULTS

Among the 212 relevant systematic reviews and meta-analyses, 57 were finally included in our analysis. These studies involved 75 diseases and 81 disease-related outcomes, with cancer (19/81) being the most frequently addressed topic. Of the 81 outcomes, 67 demonstrated a significant association. Notably, the highest risk estimate was found for head and neck cancer [odds ratio (OR) = 3.17, 95% confidence interval (CI) 1.78 - 5.64], while the lowest was observed for premature rupture of the amniotic sac [relative risk (RR) = 1.10, 95% CI 1.08 - 1.12]. The methodological quality ratings indicated that approximately 71.93% of included studies were classified as "Critically low", with another 17.54% rated as "Low", and only about 10.53% categorized as "Moderate".

CONCLUSIONS

Periodontal disease significantly elevates the risks associated with 15 cancer-related, 8 cardiovascular-related, 8 metabolic-related, and 5 neurological-related outcomes. However, the overall methodological quality of existing systematic reviews and meta-analyses is generally suboptimal and requires enhancement to generate higher-quality evidence in the future.

Link between periodontitis and diabetic retinopathy: Inflammatory pathways and clinical implications

The bidirectional relationship between periodontitis and type 2 diabetes mellitus has been well-established. However, the underlying molecular mechanisms remain unclear. Diabetic retinopathy (DR) is an important complication of diabetes, but there are few studies on the relationship between DR and periodontitis, especially on the intrinsic inflammatory pathway mechanism. This article reviews the latest clinical data on how diabetes promotes susceptibility to periodontitis from the epidemiological and molecular perspectives, with a special focus on the key roles of systemic inflammation and endothelial dysfunction in the interplay between DR and periodontitis. Comprehension of the intertwined pathogenesis of DR and periodontitis can better guide the development of comprehensive management strategies for glycemic control and periodontal health, with the aim of mitigating the progression of DR and enhancing overall well-being.

Periodontal disease: A silent factor in the development and progression of diabetic retinopathy

The global increase in the prevalence of type 2 diabetes mellitus (T2DM) and its complications presents significant challenges to public health. Recently, per-iodontal disease (PD) was recognized as a factor that is likely to influence the progression of T2DM and its complications due to its potential to exacerbate systemic inflammation and oxidative stress. In this editorial, we comment on the article published by Thazhe Poyil et al in the very recent issue of the World Journal of Diabetes in 2024, which investigated the correlation between PD and diabetic retinopathy (DR) in T2DM patients, with emphasis on the association between periodontal swollen surface area, glycated hemoglobin (HbA1c), interleukin-6 (IL-6), and lipoprotein (a). The findings by Thazhe Poyil et al are significant as they demonstrate a strong link between PD and DR in T2DM patients. This correlation highlights the importance of addressing periodontal health in diabetes management to potentially reduce the risk and severity of DR, a complication of diabetes. The integration of periodontal evaluation and treatment into diabetes care protocols may lead to improved glycemic control and better overall outcomes for T2DM patients . A few studies have established an interconnection between PD and diabetic complication, specifically DR, in T2DM patients, which we aim to highlight in this editorial. Emphasis was placed on the different mechanisms that suggest a bidirectional relationship between PD and T2DM, where the presence of periodontal inflammation negatively influenced glycemic control and contributed to the development and progression of DR through shared inflammatory and vascular mechanisms. This article highlights the importance of collaboration amongst diabetes specialists, ophthalmologists, periodontists, and public health professionals to advance the prevention, early detection, and treatment of PD and DR. This will improve the health and quality of life of T2DM patients. Moreover, the editorial highlights the need for further research on the specific molecular and immunological mechanisms that underlie the link between periodontitis and DR, with identification of common inflammatory biomarkers and signaling pathways. This is expected to facilitate effective direction of therapeutic objectives, thereby improving the management of diabetes and its complications through integrated care that incorporates oral health.

Bidirectional link between periodontitis and systemic inflammation in diabetic retinopathy

Periodontitis is independently associated with numerous lifestyle diseases. Diabetic patients have approximately threefold increased odds of periodontitis, which in turn increases the risk of systemic inflammation. The study by Thazhe Poyil et al is an effort to establish the inflammatory link between diabetic re-tinopathy (DR) and periodontitis based on the periodontal inflamed surface area in diabetic patients with and without DR. To further advance the study, we suggest refining the eligibility criteria to explicitly state the clinical correlates of periodontitis and DR, larger sample size and improved sampling methodology, matching of baseline characteristics of the two groups, as well as improved statistical approach and interpretation of the study findings. Measurement of hemoglobin A1c (HbA1c) in studies comparing type 2 diabetes mellitus patients with DR of matched severity with and without periodontitis could provide a clearer picture of whether HbA1c level is indeed influenced by periodontitis.

Diabetes Mellitus and Periodontal Disease: A New Perspective

First recorded in 1928, people living with diabetes mellitus (DM) are at a three to four times higher risk of developing periodontal disease (PD) than non-diabetics; for those who smoke this risk increases up to ten times. However, many doctors are unaware of this.DM and PD are bidirectionally linked, the one affecting the other and vice versa, although the mechanism is not fully understood and may be linked to chronic infection. PD has an adverse effect on glycaemic control. That improves when periodontitis is successfully treated.Doctors should consider PD when their patients have persistently high glycated haemoglobin (HbA1c) levels, and dentists should consider diabetes or pre-diabetes when they have patients with unstable or progressive periodontitis.Doctors, dentists, and their teams need to share results. A traffic light system of red, amber and green for both medical and dental risks is proposed, and a pro forma designed, so that diabetics themselves can share them with their professional advisors until such times as there are reliable methods of interprofessional communication and a paradigm shift in working practices is achieved.Dentists need to find ways to teach their medical colleagues about the basics of PD, update their medical records, and understand more about medical risks. More research is required.

The rosetta stone of successful ageing: does oral health have a role?

Ageing is an inevitable aspect of life and thus successful ageing is an important focus of recent scientific efforts. The biological process of ageing is mediated through the interaction of genes with environmental factors, increasing the body's susceptibility to insults. Elucidating this process will increase our ability to prevent and treat age-related disease and consequently extend life expectancy. Notably, centenarians offer a unique perspective on the phenomenon of ageing. Current research highlights several age-associated alterations on the genetic, epigenetic and proteomic level. Consequently, nutrient sensing and mitochondrial function are altered, resulting in inflammation and exhaustion of regenerative ability.Oral health, an important contributor to overall health, remains underexplored in the context of extreme longevity. Good masticatory function ensures sufficient nutrient uptake, reducing morbidity and mortality in old age. The relationship between periodontal disease and systemic inflammatory pathologies is well established. Diabetes, rheumatoid arthritis and cardiovascular disease are among the most significant disease burdens influenced by inflammatory oral health conditions. Evidence suggests that the interaction is bi-directional, impacting progression, severity and mortality. Current models of ageing and longevity neglect an important factor in overall health and well-being, a gap that this review intends to illustrate and inspire avenues for future research.

Codon Pattern and Compositional Constraints Determination of Genes Associated with Chronic Periodontitis

Genome-wide association studies showed the relationship of NIN, ABHD12B, WHAMM, AP3B2, and SIGLEC5 with chronic periodontitis. The study’s objective was to investigate different molecular patterns and evolutionary forces acting on the mentioned genes. The investigation of molecular patterns encompasses the study of compositional parameters, expression profile, physical properties of genes, codon preferences, degree of codon bias, determination of the most influential codons, and assessment of actions of evolutionary forces, such as mutations and natural selection. The overall compositional analysis revealed the dominance of A and G nucleotides compared to T and C. A relatively low codon usage bias is observed. The CTG codon is the most overused codon, followed by TCC. The genes, AP3B2 and SIGLEC5, preferred GC-ending codons, while NIN, ABHD12B, and WHAMM preferred AT-ending codons. The presence of directional mutational force and natural selection was found to operate codon usage in genes envisaged, and selective forces were dominant over mutational forces. Apart from mutation and selection forces, compositional constraints also played imperative roles. The study enriched our knowledge of specific molecular patterns associated with the set of genes significantly associated with chronic periodontitis. Further studies are warranted to identify more genetic signatures associated with the disease.

Periodontal diseases assessed by average bone resorption are associated with microvascular complications in patients with type 2 diabetes

Periodontal disease often develops in patients with diabetes, and further exacerbated with diabetic complications. It would be clinically important to clarify the relationship between diabetic microvascular diseases and periodontal disease. This study aimed to evaluate the association between periodontal disease and diabetic complications in patients with type 2 diabetes with poor glycemic control. A total of 447 patients with type 2 diabetes hospitalized at Rakuwakai Otowa Hospital, Japan, were initially recruited in this study. After excluding 134 patients who lacked clinical data or were edentulous, 312 were included in our study. The severity of periodontal disease was evaluated based on the average bone resorption rate. Patients with diabetic nephropathy developed severe periodontal disease (multivariate-adjusted odds ratio, 3.00 [95% CI 1.41-5.19]). Diabetic neuropathy was positively associated with the severity of periodontal disease; the multivariate-adjusted odds ratio (95% CI) was 1.62 (0.87‒2.99) for moderate and 4.26 (2.21‒8.20) for severe periodontal disease. In contrast, diabetic retinopathy was linked with moderate periodontal disease (multivariate-adjusted odds ratio 2.23 [95% CI 1.10-4.10]), but not with severe conditions (multivariate-adjusted odds ratio 0.92 [95% CI 0.67-3.07]). In conclusion, periodontal disease, evaluated by average bone resorption rate, was associated with diabetic nephropathy and neuropathy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13340-022-00591-0.

Cross-Cohort Microbiome Analysis of Salivary Biomarkers in Patients With Type 2 Diabetes Mellitus

Several studies have ascertained differences in salivary microbiota between patients with type 2 diabetes mellitus (T2DM) and healthy populations. However, the predictive accuracy and reproducibility of these 16S rRNA sequencing analyses when applied to other cohorts remain enigmatic. A comprehensive analysis was conducted on the included 470 samples from five researches in publicly available databases. The discrepancy and predictive accuracy of salivary microbiota between T2DM patients and healthy populations were evaluated from multiple perspectives, followed by the identification of salivary biomarkers for DM. Next, a classification model (areas under the curves = 0.92) was developed based on a large sample. The model could be used for clinical diagnosis and prognostic monitoring and as a basis for hypothesis-driven mechanistic researches. Furthermore, the research heterogeneity across geographic regions suggested that microbiological markers might not become a uniform clinical standard in human beings. They rather identify abnormal alterations under the microbiological characteristics of a specific population.

Novel Insight into the Mechanisms of the Bidirectional Relationship between Diabetes and Periodontitis

Periodontitis and diabetes are two major global health problems despite their prevalence being significantly underreported and underestimated. Both epidemiological and intervention studies show a bidirectional relationship between periodontitis and diabetes. The hypothesis of a potential causal link between the two diseases is corroborated by recent studies in experimental animals that identified mechanisms whereby periodontitis and diabetes can adversely affect each other. Herein, we will review clinical data on the existence of a two-way relationship between periodontitis and diabetes and discuss possible mechanistic interactions in both directions, focusing in particular on new data highlighting the importance of the host response. Moreover, we will address the hypothesis that trained immunity may represent the unifying mechanism explaining the intertwined association between diabetes and periodontitis. Achieving a better mechanistic insight on clustering of infectious, inflammatory, and metabolic diseases may provide new therapeutic options to reduce the risk of diabetes and diabetes-associated comorbidities.

Huoxue Jiangtang Decoction Alleviates Type 2 Diabetes Mellitus by Regulating the Oral Microbiota and Food Preferences

PURPOSE

As a formula of traditional Chinese medicine (TCM), Huoxue Jiangtang Decoction (HJD) has positive effects on diabetes mellitus (DM) through improving of the metabolism of glycolipid and the function of β-cell. Hence, this research aims to explore the potential therapeutic effects of HJD on diabetes and reveal its underlying mechanisms.

METHODS

Diabetic rat models induced by high-fat diet (HFD) and streptozotocin (STZ) were included in this study. Following successful modeling, diabetic rats were treated with HJD, and then its therapeutic effects in eight weeks were evaluated. In addition to biochemical indicators, two-bottle preference tests were carried out to examine the rats' preferences for fat and sugar, and 16S rRNA gene sequencing was performed to disclose the differences of oral microbiota among groups. Finally, Pearson correlation coefficient was used to explore the correlation between oral microbiota and the preferences for fat and sugar.

RESULTS

It was found that HJD significantly improved the levels of fasting blood glucose (FBG), glucose tolerance, and dyslipidemia. Additionally, HJD contributed to decreasing preferences for fat and sugar in diabetic rats, which plays an important role in food intake. Furthermore, HJD regulated the abundance, distribution, and structure of oral microbiota in diabetic rats, serving as one of the underlying mechanisms of its antidiabetic effects.

CONCLUSION

Taken with other formulas, HJD functions to improve the metabolism of glycolipid and the function of β-cell by inhibiting preferences for fat and sugar, as well as regulating the oral microbiota of diabetic rats. Furthermore, a potential correlation between the oral micro-environment and preferences for fat and sugar in STZ-induced diabetic rats is likely to exist.