Diabetes 2013 July-19


Relationship between oral health, diabetes management and sleep apnea

Cinar AB, Oktay I, Schou L. aci@sund.ku.dk

Clin Oral Investig. 2013 Apr; 17(3):967-74. doi: 10.1007/s00784-012-0760-y. Epub 2012 May 31




The aim of this study was to assess the relationship between tooth loss, toothbrushing behaviour, diabetes type 2 (DM2), obesity and sleep apnea among diabetics.


DM2 patients (n = 165) in Istanbul, Turkey, were randomly selected from the outpatient clinics of two hospitals. Baseline clinical measurements (HbA1c, fasting blood glucose, high-density lipoprotein (HDL), low-density lipoprotein (LDL), body mass index (BMI), body-fat proportion, tooth loss) and self-administered questionnaires (toothbrushing, gingival bleeding, sleep apnea) provided data for factor and principal component analysis with Varimax rotation. Univariate statistics and chi-square tests were derived.


Mean maxillary tooth loss (4.49 ± 3.69 teeth) was higher than in the mandible (3.43 ± 3.12 teeth, p< 0.001). Favourable HDL was measured among most patients (77%); other favourable clinical measures occurred only in a minority of participants (HbA1c, 28%; fasting blood glucose, 17%; LDL, 30%). Twice daily toothbrushing was reported by 33% (17%) for healthy BMI; 37% when healthy body-fat proportions. There was risk of sleep apnea in 37%. The higher number of lost teeth in the maxilla was linked with obesity and sleep apnea. Non-daily toothbrushers were more likely to have high LDL and low HDL cholesterol and a higher risk of sleep apnea. When “at least occasionally” bleeding on toothbrushing occurred, higher HbA1c levels and sleep apnea were more likely.


Based on the correlations found between oral health (clinical and self-assessed) and diabetes-related variables, oral care may play a major role in the prevention of further complications of DM2 by enabling early diagnosis and monitoring of poor diabetes management


  1. Observation of frequent gingival bleeding and subsequent tooth loss may lead patients to consider the risk of sleep apnea, and to have appropriate clinical examinations early. Dentists may also play a key role in better managing and diagnosing sleep apnea early, by referring the patients with severe tooth loss and periodontal disease for general medical examination.
  2. It could be relevant for physicians to be prepared inform their DM2 patients about managing their oral and general health, to prevent possible further complications. 
  3. There seems to be need for public health programs, training programs and campaigns to increase the awareness among health care professionals and patients about the relationships between oral health, diabetes and sleep apnea. Future research on these factors is essential to counter the pandemic of DM2 complications and poor oral health.


Current scientific evidence suggests that oral diseases, diabetes mellitus type 2 (DM2), and obesity share common risk factors (poor dietary habits, a sugar-rich diet, smoking) [1-5] and biologic mechanisms [6-11]. Periodontal disease, one of the most common oral diseases, is a major cause of tooth loss.  Studies establishing the relationship among DM2, periodontal health and subsequent tooth loss have been widely reported [12-14]. Obesity is a significant risk factor for DM2 and periodontal diseases [8, 9] and tooth loss [10, 11]. However, there has been no study, to our knowledge, about the links between DM2 and obesity and tooth loss.

Obstructive sleep apnea (OSA) is a common and treatable form of sleep-disordered breathing, involving upper airway collapse during sleep [12]. Obesity is recognized as the strongest risk factor for OSA [13, 14]. It is unknown whether DM2 contributes to the development or aggravation of OSA, although this is likely [12]. Conversely, OSA may be a risk factor for DM2; strong evidence suggests that OSA may increase the risk of developing DM2. Tooth loss may favour the occurrence of OSA; the absence of teeth produces prominent anatomical changes that may influence upper airway size and function, such as loss of the vertical dimension of occlusion, reduction of the lower face height and mandible rotation [15]. The role of tooth loss in OSA has been a neglected issue.

The present study aimed to assess the links between tooth loss, oral health behaviour, DM2, obesity, and sleep apnea among patients with DM2.

Our findings can be summarized as:

  1. HbA1c was correlated with the total number of teeth lost and the numbers lost in each jaw. HbA1c and the number of teeth lost in the upper jaw were positively correlated with self-reported gingival bleeding, suggesting that these three factors share lifestyle or pathogenic factors or factors such as an increased inflammatory reaction due to destruction of periodontal tissue. Therefore, gingival bleeding observed by the patient may signify initial inflammation which may lead to periodontal tissue destruction, subsequent tooth loss and increase in blood glucose. Self-reported gingival bleeding may thus be looked on as an early risk indicator for tooth-loss and high HbA1c levels.
  2. Toothbrushing frequency among DM2 patients was positively correlated with HDL and negatively with fasting blood glucose. This should be verified in future studies, as the present study is among  extremely few publications, to our knowledge, that investigate the link between toothbrushing frequency and diabetes management, measured in terms of fasting blood glucose and HDL.
  3. The link between tooth loss, OSA and BMI, in terms of correlation and clustering, may imply that tooth loss, in particular in the maxilla, seems to be an important predisposing factor, either by leading to anatomical changes or signaling active periodontal infection. The correlation between maxillary tooth loss and HbA1c and fasting blood glucose may imply some underlying pathogenic or biologic mechanisms between OSA, tooth loss and DM2. This may have important public health implications and lead to improved health and oral health among DM2 patients. Daily toothbrushing may act as a preventive health behaviour in the prevention of OSA by reducing gingival inflammation, considering the correlation of OSA with toothbrushing and gingival bleeding in the present study. There is a vital need for further research to understand better the relationship between OSA, tooth loss, diabetes and obesity, as this is the first study exploring this relation as far as we know.

Ayse Basak Cinar1 was lead author in this study and thanks his co-authors Prof. Inci Oktay2, Prof.Lone Schou3. She is an assistant professor at Institute of Odontology, University of Copenhagen. She has doctorate at odontology (MSc, PhD) and she is a professional health coach. The present study is a part of international intervention assessing the impact of health coaching among patients with diabetes type 2. Facebook link to the study is https://www.facebook.com/want2smile2yourdiabetes. Dr.Cinar can be contacted via email at aci@sund.ku.dk

¹Oral Public Health Department, Institute of Odontology, University of Copenhagen, Denmark-Copenhagen;²Oral Public Health Department, Yeditepe Dental Faculty, Istanbul-Turkey ; 3 Global  Oral  Health Promotion Section, Faculty of Medical Sciences,  University of Copenhagen, Denmark-Copenhagen



Table 1. Background characteristics of the participants (n = 165)

Ayse Basak Cinar-1

*12.3 years=mean


Table 2. The proportion of Turkish diabetes mellitus type 2 patients with unfavourable clinical measures and the
probability of sleep apnea and oral health-related factors

Ayse Basak Cinar-22

* Statistical evaluation: by chi-square test, differences by favourable clinical measures.

*P < 0.05, **P=0.056


Table 3. Factor Analysis assessing oral health and diabetes related clusters of “lost maxillary teeth” (below mean vs. mean or above), among Turkish patients with diabetes mellitus type 2, by Varimax rotated solution

Ayse Basak Cinar-33

UJ: Upper jaw

The clusters in the study group, in total, accounted for 59.6% of the total variance (composed of component1:16.7%, component2: 15.8% and component3: 14.5%, component4: 12.5 %)

All variables as favourable (0) and unfavourable (=1) along with health measures (rare gingival bleeding on brushing= 0, non-obese = 0).

Body-fat proportion was not included in analysis due to its high correlation with BMI.

*Loadings below 0.25 extracted for ease of communication.  The clusters are named based on the variable with highest loading.



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