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Glycemic control of diabetics may improve slightly with periodontal treatment

Hope Saltmarsh RDH, BA, MEd .


Systematic Review Conclusion

Periodontal therapy for type 2 diabetic patients with periodontitis can reduce A1C (glycated hemoglobin) levels on average by 0.40% for at least 3 months.

Critical Summary Assessment

A small number of studies with clinical diversity show that glycemic control of diabetic patients may improve slightly with periodontal therapy.

Evidence Quality Rating

Limited Evidence

Structured Abstract

Clinical Questions:

In diabetic patients, does periodontal treatment improve glycemic control for at least 3 months compared to no periodontal treatment?

Review Methods:

The authors searched two electronic databases for English-only publications from January 1960 to March 31, 2009. Inclusion criteria were controlled clinical trials (CCT) and randomized clinical trials (RCT) of at least three months’ duration conducted in diabetic patients with periodontitis. The required outcomes were measures of metabolic control including A1C levels.

Main Results:

The review included three RCTs and two CCTs, both of which totaled 199 treated patients and 183 control patients. All patients had type 2 diabetes and periodontitis. Periodontal treatment was scaling and root planning, with or without antibiotic therapy. All studies reported absolute change in A1C. A1C levels of 8 percent and less are considered good and 10 percent and above are considered poor. All studies showed an improved (decreased) A1C level in treated patients ranging from a reduction of 0.05 to 1.17 percent. This improvement was statistically significant in only two studies. Meta-analysis of the five studies resulted in a weighted mean difference (WMD) of -0.40percent between treated group and control.


Periodontal therapy for type 2 diabetics with periodontitis improves glycemic control and can reduce A1C levels on average, by 0.40 percent more than nonintervention therapies.

Source of Funding:

College of Health Insurance, Amsterdam, the Netherlands


Importance and Context:

According to current projections, the annual diagnosis of new cases of diabetes in the United States will increase from about 8 cases per 1,000 in 2008 to about 15 in 2050. Diabetes is associated with increased prevalence and progression of periodontitis. People with diabetes who have periodontal infection have poorer glycemic controls than diabetic patients without infection. The authors hypothesized that if periodontitis is causally related to a worsening of diabetic signs, then periodontal treatment should improve glycemic control.

Strengths and Weaknesses of the Systematic Review:

The methodological quality of this systemic review, did not meet some of the quality criteria set forth in the AMSTAR checklist. The literature search was not comprehensive; the authors searched only two electronic databases for English-only publications. They did not state who conducted the search, who selected the studies, and who extracted the data. These limitations introduce the possibility of reviewer bias. The authors judged the three RCTs as good quality and the two CCTs as doubtful quality, based on their assessment of allocation concealment, randomization, blindness, and loss to follow-up. They failed to explain why they used CCTs in their meta-analysis or how their inclusion affected the results.

Strengths and Weaknesses of the Evidence:

A1C levels reflect blood glucose levels over the preceding one to three months. This most valuable measure of metabolic control was reported in all studies. Fasting plasma glucose (FPG) results reported in three studies were conflicting, statistically insignificant, and measured glycemic control at only one moment in time. Only one study reported levels for both C-reactive protein (CRP) and postprandial glucose (PPG). The paucity of studies and the small size of the study groups both weaken the strength of evidence. The meta-analysis showing a WMD of -0.40percent in A1C levels for the treatment group had a wide confidence interval (95 percent CI, -0.77 percent to -0.04 percent), which indicates a lack of precision in the estimate of effect. The meta-analysis lacked robustness due to significant heterogeneity among the studies. The CCTs introduced bias by placing treatment avoiders in the control groups. Baseline A1C levels generally reflected poor glycemic control. However, some subjects in two of the RCTs had good control, which may have affected their treatment results. The studies used different or unstated definitions of periodontitis. When antibiotics were used, the protocols changed. Only two studies reported subjects who significantly improved their glycemic control. One of these studies, a CCT, had doubtful quality and the other, an RCT, included some patients with good baseline A1C levels. The results of the meta-analysis should be viewed with caution. The authors of another Cochrane review on this topic (May 2010) conducted a more comprehensive search that yielded seven RCTs. In their review, those authors pooled the results of three studies (two of which this review included) for meta-analysis of A1C levels, their results were identical to those of this review.

Implications for Dental Practice:

For a diabetic patient with periodontitis, improving periodontal health with therapy is an important goal. There is limited evidence that periodontal treatment may slightly improve glycemic control. From a clinical perspective, any decrease in A1C levels should result in fewer medical diabetic complications. More robust trials are needed to specifically recommend periodontal treatment solely for the purpose of improving glycemic control.

Critical Summary Publication Date:


These summaries are not intended to, and do not, express, imply, or summarize standards of care, but rather provide a concise reference for dentists to aid in understanding and applying evidence from the referenced systematic review in making clinically sound decisions as guided by their clinical judgment and by patient needs. American Dental Association © 2019