Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease in which there is ongoing hyperglycemia due to insulin resistance, insulin deficiency, or both.[1] It is the most common type of diabetes, and it is responsible for 90-95% of diabetes worldwide.[2] The International Diabetes Federation (IDF) estimates that currently there are over ‘530 million adults living with diabetes worldwide and that this figure will increase to over 780 million by 2045’, with a rapidly growing burden on public health.[3] The burden of diabetes has also greatly increased in low and middle-income countries, including Pakistan, where the changing dietary pattern, sedentary lifestyle, obesity, and genetic susceptibility are responsible for the increased incidence of T2DM.[4]

In diabetes, chronic hyperglycemia causes advanced glycation end product production, oxidative stress, endothelial dysfunction, and dysfunction of the immune system, and this is the cause of microvascular and macrovascular complications.[5] Oral complications of diabetes are well-recognized and now emerging as an important clinical manifestation, while systemic complications like nephropathy, retinopathy, neuropathy, and cardiovascular disease have been well researched.[5] The oral cavity can be a clinical indicator of the metabolic state of diabetic patients, and several oral problems have been associated with inadequate blood sugar control and long duration of diabetes.[6]

The oral changes that are reported in patients with T2DM are periodontal disease, xerostomia, dental caries, oral infections, delayed wound healing, burning mouth sensation, taste alteration, and mucosal changes.[6] The mutual relationship between diabetes and periodontal disorders is a significant complication.[7]  Hyperglycemia induces inflammatory cytokines, which lead to periodontal tissue destruction and decrease host defense mechanisms, leading to greater susceptibility to destruction, and periodontal inflammation could further contribute to insulin resistance and glycemic control.[8] In the same way, diabetic patients have various changes in their saliva, including low levels, changes in composition, and increased bacterial counts, which can lead to dental caries, bacterial overgrowth, and oral pain.[9]

Glycated hemoglobin (HbA1c) is regarded as an excellent index of long-term glycemic control, as it represents average glucose levels over the last 2-3 months.[10] HbA1c level is a strong predictor of diabetic complications.[11]

The burden of T2DM and the possible presence of oral changes as clinical markers of metabolic status warrant further investigation. Further research could help confirm the association between oral and HbA1c testing, enabling the use of oral examination as a simple, cost-effective supportive assessment tool in diabetic care. Thus, the aim of this study was to assess the prevalence of oral changes in T2DM patients and to investigate the relationship between the oral changes and the HbA1c level in the hospital-based population. The aim of this study was to assess the prevalence of oral manifestations in patients with type 2 diabetes mellitus and evaluate their association with HbA1c levels to determine the relationship between oral health status and glycemic control.

The prevalence of oral complaints and their relationship to glycemic control, as determined by HbA1c levels, was examined in a cross-sectional, analytical study conducted at a hospital setting in patients with type 2 diabetes mellitus. The study duration was six months, from July to December 2025. The sample size was determined using the OpenEpi sample size calculator with the following factors; 95% confidence level, 8% margin of error, and the prevalence of oral manifestations among patients with type 2 diabetes mellitus being reported at 50%.[12] A sample size of 150 participants was calculated. Participants were recruited using a non-probability consecutive sampling technique. The patients diagnosed with type 2 diabetes mellitus who met the inclusion criteria and attended the Medicine and Dentistry/Oral Medicine outpatient departments during the study period were consecutively recruited until the required sample size was reached. The sampling method chosen was to include available diabetic patients from the hospital setting and to ensure representation of patients with varying glycemic control. The study included patients with a confirmed diagnosis of type 2 diabetes mellitus aged ≥18 years. Participants were those diagnosed with diabetes at least six months prior who were being followed up or treated at the hospital regularly. Informed consent and consent to undergo oral examination and HbA1C testing was obtained from patients who were interested in and available for these tests. To assess oral manifestation frequency among different demographic groups, both men and women patients were included. The study excluded patients with type 1 diabetes mellitus (T1DM), gestational diabetes, and other diabetes specific types. People with systemic diseases or conditions that might impact oral health independently were excluded, including autoimmune diseases, malignancies of the body, and severe immunodeficiency. Patients who received dental treatment within the previous year, received potentially drug-affecting medications or presented with incomplete clinical and/or laboratory records were also excluded. The participants who did not give informed consent or refused the participation were excluded from the study. Ethical clearance and informed consent were first obtained from the study participants and data were gathered from patients who had been diagnosed with type 2 diabetes mellitus in the hospital outpatient departments. Structured data collection proforma was used to record demographic data such as age, gender, duration of diabetes, treatment history and clinical characteristics relevant to the study. A detailed oral examination was conducted under good light, with normal dental instruments, in each participant. This examination was aimed at determining the common oral manifestation of diabetes such as periodontal disease, xerostomia, dental caries, oral mucosal lesions, candidiasis, and burning mouth sensation and delayed oral wound healing. The periodontal status of participants was evaluated by clinical examination, and the symptoms associated with decreased salivary secretion and oral discomfort were noted based on the history and clinical examination. Patient records and interviews were used to gather medical data relevant to diabetes, such as duration and current antidiabetic treatment. Laboratory analysis of glycated hemoglobin (HbA1c) was used to measure glycemic control. HbA1c level was obtained for each patient and grouped by glycemic control status. All the collected data was checked for completeness and compiled in a database for statistical analysis. The data were analyzed with the help of the Statistical Package for Social Sciences (SPSS) version 26.0. Continuous variables like age, duration of diabetes, and HbA1c level were reported as mean ± SD or median (IQR) as appropriate. The categorical variables, such as gender, presence of oral manifestations, and glycemic control categories, were shown as frequencies and percentages. The chi-square test and Fisher's exact test was used to evaluate the association between oral manifestations and HbA1C levels as appropriate. An independent sample t-test was used to compare HbA1c levels of patients with and without oral complications. Pearson's association analyses were used for evaluating the association between the severity of the oral manifestations and HbA1C. P-values ≤ 0.05 were considered statistically significant.

A total of 150 patients with type 2 diabetes mellitus were included in the study. The mean age of participants was 53.4 ± 11.2 years, with the majority belonging to the 41–60 years age group. There were marginally more male patients than female patients. The duration of diabetes was mostly 5–10 years, and the most commonly used treatment was oral hypoglycemic therapy. (Table 1)

Assessment of glycemic status showed that poor glycemic control was found in the participants, and a large portion had elevated HbA1c levels. The oral manifestations were present in most diabetic patients, and only a few had no detectable oral complications. The severity pattern revealed a greater number of oral manifestations than expected in patients with diabetes, as many patients had more than one oral problem. (Table 2)

The oral complication most commonly found was periodontal disease, followed by xerostomia and dental caries. Other reported characteristics were gingival inflammation, oral candidiasis, burning mouth sensation, delayed healing of oral wounds, mucosal lesions, and taste disturbances. (Table 3)

There was a significant association between the occurrence of oral manifestation with age and diabetes duration, respectively. Patients with a longer duration of diabetes showed more complications in the oral cavity, implying that long duration of hyperglycemia can be responsible for its progressive tissue changes. (Table 4)

Patients with oral diseases such as periodontitis, oral candidiasis, xerostomia, dental caries, gingival bleeding, and burning tongue sensation had significantly higher HbA1c levels than patients without these oral diseases. The greatest association with poor glycemic control was with periodontitis and oral candidiasis, indicating that poorer metabolic control was also associated with a greater burden of oral disease. The results here suggest that there is a strong relationship between hyperglycated haemoglobin and inflammatory/infective oral lesions in patients suffering from type 2 diabetes mellitus. (Table 5)

Overall oral health status showed that oral health patients had significantly higher mean values of HbA1C levels compared to those without oral health issues. Additionally, a direct relationship between worsening oral involvement and worsening glycated hemoglobin levels was observed, as worsening oral involvement was associated with worsening HbA1c levels. (Table 6)

A significant positive association was found between HbA1c levels, the duration of diabetes, and the severity of oral manifestations through association analysis. An increased HbA1c value was associationwith an increase in oral complication scores, and there was a moderate association between longer duration of disease and worsening oral findings. (Table 7)

Table 1. Demographic and Clinical Characteristics of Patients with Type 2 Diabetes Mellitus (n=150)

Table 2. Distribution of HbA1c Levels and Oral Manifestations Among Study Participants (n=150)

Table 3. Frequency and Pattern of Oral Manifestations in Patients with Type 2 Diabetes Mellitus (n=150)

Table 4. Association of Clinical Characteristics with Presence of Oral Manifestations (n=150)

Table 5. Relationship Between HbA1c Levels and Specific Oral Manifestations (n=150)

Table 6. Comparison of Mean HbA1c Levels According to Oral Health Status (n=150)

Table 7. Association Analysis Between Diabetes Parameters and Oral Manifestation Severity

The current study aimed to determine the prevalence of oral abnormalities among type 2 diabetes mellitus patients and to find their relationship to HbA1C values. In this study, more than half of the diabetic patients had oral manifestations, of which periodontitis, xerostomia, and dental caries were the most prevalent. There was a strong relationship seen between the occurrence of oral complications and poor glycemic control, with patients having high HbA1C levels showing higher oral disease burden. The present result confirms that chronic hyperglycemia causes inflammatory activation, immune dysfunction, dysfunction of salivary function, and slow wound healing in oral tissues.

This high prevalence of periodontal disease seen in our study is in line with previous studies showing that diabetes is an important risk factor for periodontal inflammation.[13, 14] There have been recent reports that those with uncontrolled diabetes have higher levels of periodontal destruction, likely as a result of greater release of inflammatory mediators and an impairment in neutrophil function.[8] Similar to the present study, other studies found periodontitis was among the most common oral complications in the diabetic population and that high HbA1c levels were associated with increased periodontal severity.[15, 16] The bidirectional connection between diabetes and periodontal disease is well supported by evidence, with diabetes worsening periodontal inflammation, and periodontal infection being a risk factor for insulin resistance and impaired glycemic control.[8]

We found xerostomia to be a frequent oral symptom among diabetics, which is in line with findings from recent observational study indicating that T2DM is associated with decreased salivary flow and altered salivary composition.[17] Dry mouth may be caused by hyperglycemia-related dehydration, autonomic dysfunction, and/or the effects of medications. Research conducted has also shown that patients with poor metabolic control have worse symptoms of dry mouth, more discomfort in the mouth, and a higher risk of opportunistic infections.[18]

In the present study, a significant association was found between HbA1C levels and the oral manifestations, where patients with poor HbA1C had significantly greater numbers of oral complications. Consistent findings were also observed in recent research assessing the severity of oral disease in hospital and dental care environments, in which HbA1c was found to be a key predictor of oral disease.[19] High HbA1c levels indicate the presence of chronic hyperglycemia that leads to advanced glycation end-products, oxidative stress, and inflammatory responses, making the oral tissues more susceptible.[20]

Previous studies have also reported an association between diabetes duration and oral complications similar to the present study. Studies have been published reporting that those who have had diabetes longer than 5-10 years are at greater risk of developing periodontal disease, candidiasis, and mucosal changes than are those who have recently been diagnosed.[21] This can be attributed to the effects of repeated metabolic injury, gradual blood vessel damage and sustained immune dysfunction. Hence, the duration of diabetes seems to be a significant factor in the oral health status.

Our findings also corroborate earlier studies suggesting the importance of incorporating the assessment of oral health into the management of diabetes.[22] Recent research has highlighted the benefits of oral examination in shedding light on a patient's metabolic status, especially in resource-constrained health care environments where complete monitoring might be difficult.[23] Immediate diagnosis of oral changes can enable prompt dental intervention and better glycemic control by a multidisciplinary approach involving physicians and dentists.

Our results showed that HbA1c was positively association with the severity of oral manifestation, which has been reported by recent investigators who studied oral manifestation in diabetic patients and reported a significant association between them.[24] Likewise, diabetic periodontal studies showed that periodontal outcomes were better and the inflammation burden was reduced with enhanced glycemic control.[7, 25] These observations suggest that the oral presentation could be used as a further biomarker of glycemic control.

In conclusion, the present study results corroborate those of other studies showing that dental alterations are not infrequent in persons with type 2 diabetes mellitus and that poor glycemic control is significantly related to these disease manifestations. The high oral disease-HbA1c association reinforces the need to screen for oral disease as a part of comprehensive diabetes care. Regular dental examinations can play a role in the early identification of poor metabolic control and in minimizing the effects of diabetes on oral health with early preventive and therapeutic intervention.

The present study showed that oral manifestations among type 2 diabetes mellitus patients are highly prevalent and are significantly associated with HbA1c levels. Oral complications most commonly reported were periodontitis, xerostomia, and dental caries, and these complications were more common in patients with poor glycemic control and longer years of diabetes. The results emphasize the need to include a routine oral health assessment component in diabetes management programs, because oral assessments can be helpful tools for metabolic control. A dental-medical team could enhance early detection, prevention, and management of oral complications of diabetes.

1. Rachdaoui, N., Insulin: the friend and the foe in the development of type 2 diabetes mellitus. International journal of molecular sciences, 2020. 21(5): p. 1770.
2. Marrs, J.C. and S.L. Anderson, Ertugliflozin in the treatment of type 2 diabetes mellitus. Drugs in Context, 2020. 9.
3. Ahmed, H. and I. Ahmed, Introduction to type 2 diabetes mellitus (T2DM), in Type 2 Diabetes Mellitus. 2026, Elsevier. p. 1-25.
4. Liu, J., et al., Low-and middle-income countries demonstrate rapid growth of type 2 diabetes: an analysis based on Global Burden of Disease 1990–2019 data. Diabetologia, 2022. 65(8): p. 1339-1352.
5. Khalid, M., G. Petroianu, and A. Adem, Advanced glycation end products and diabetes mellitus: mechanisms and perspectives. Biomolecules, 2022. 12(4): p. 542.
6. Ahmad, R. and M. Haque, Oral health messiers: diabetes mellitus relevance. Diabetes, Metabolic Syndrome and Obesity, 2021: p. 3001-3015.
7. Bolchis, V., et al., Glycemic control, inflammatory mediators, and periodontal health: A cross-sectional study in patients with diabetes. Journal of clinical medicine, 2025. 14(8): p. 2847.
8. Ranbhise, J.S., et al., Chronic inflammation and glycemic control: exploring the bidirectional link between periodontitis and diabetes. Dentistry Journal, 2025. 13(3): p. 100.
9. Dey, A.K., et al., From Glucose to Gums: Exploring the Oral Side of Diabetes. J Dent Oral Health, 2023. 10: p. 1-16.
10. Dunn, T.C., et al., Personalized glycated hemoglobin in diabetes management: closing the gap with glucose management indicator. Diabetes Technology & Therapeutics, 2023. 25(3_suppl): p. S-65-S-74.
11. Ceriello, A., et al., HbA1c variability predicts cardiovascular complications in type 2 diabetes regardless of being at glycemic target. Cardiovascular Diabetology, 2022. 21(1): p. 13.
12. Ramamurthy, J., Prevalence of oral mucosal lesions in patients with type II diabetes mellitus: A retrospective analysis. World Journal of Dentistry, 2023. 14(8): p. 683-687.
13. Zhao, M., et al., Diabetes mellitus promotes susceptibility to periodontitis—novel insight into the molecular mechanisms. Frontiers in endocrinology, 2023. 14: p. 1192625.
14. Păunică, I., et al., The bidirectional relationship between periodontal disease and diabetes mellitus—a review. Diagnostics, 2023. 13(4): p. 681.
15. Rahim, A., et al., Association and comparison of periodontal and oral hygiene status with serum HbA1c levels: a cross-sectional study. BMC Oral Health, 2023. 23(1): p. 442.
16. Adhenkavil Radhakrishnan, R., R. Joseph Vadakkekuttical, and C. Radhakrishnan, Proportion and severity of periodontitis and correlation of periodontal inflamed surface area with glycemic status in patients with type 2 diabetic neuropathy with and without diabetic foot. Journal of Periodontology, 2022. 93(5): p. 687-696.
17. Sakanaka, A., et al., Diabetes alters the supragingival microbiome through plasma-to-saliva migration of glucose and fructose. Microbiome, 2026. 14(1): p. 48.
18. Hayslett, R.L. and L.L. Marshall, Management of dry mouth. The Senior Care Pharmacist, 2025. 40(2): p. 55-63.
19. Chatzopoulos, G.S. and L.F. Wolff, Prevalence, severity, and distribution of tooth mobility and association with patient-related factors in a large university-based dental cohort: an exploratory study. Journal of Dentistry, 2025: p. 106024.
20. Legiawati, L., The role of oxidative stress, inflammation, and advanced glycation end product in skin manifestations of diabetes mellitus. Current Diabetes Reviews, 2022. 18(3): p. 87-92.
21. Grisi, D.C., et al., The complex interrelationship between diabetes mellitus, oral diseases and general health. Current Diabetes Reviews, 2022. 18(3): p. 8-22.
22. Petropoulou, P., et al. Oral health education in patients with diabetes: a systematic review. in Healthcare. 2024. MDPI.
23. Adeola, H.A., et al., The practicality of the use of liquid biopsy in early diagnosis and treatment monitoring of oral cancer in resource-limited settings. Cancers, 2022. 14(5): p. 1139.
24. Costa, R., et al., The Relationship of HbA1c Serum Levels with the Severity of Periodontal Disease in Patients with Type 1 Diabetes Mellitus: A Cross-Sectional Study. European Journal of Dentistry, 2025. 19(02): p. 438-448.
25. Santonocito, S., et al., Impact of periodontitis on glycemic control and metabolic status in diabetes patients: current knowledge on early disease markers and therapeutic perspectives. Mediators of inflammation, 2022. 2022(1): p. 4955277.