Treatment of periodontal disease for glycaemic control in people with diabetes

Terry C. Simpson, Janet E. Clarkson, Helen V. Worthington, Laura MacDonald, Jo C. Weldon, Ian Needleman, Zipporah Iheozor-Ejiofor, Sarah H. Wild, Ambrina Qureshi, Andrew Walker, Veena A. Patel, Dwayne Boyers, Joshua Twigg

Does treatment for gum disease help people with diabetes control blood sugar levels?

Review question

The main question addressed by this review is: how effective is gum disease (periodontitis) treatment for controlling blood sugar levels (known as glycaemic control) in people with diabetes, compared to no active treatment or usual care?


The aim of treating periodontitis is to reduce swelling and infection and stabilise the condition of the gums and supporting bone. The level of sugar in the blood is too high in people with diabetes, so keeping blood sugar levels under control is a key issue. Some clinical research suggests a relationship exists between gum disease treatment and glycaemic control. 

Glycaemic control can be measured in different ways. For this review, we focused on HbA1c, which shows average blood glucose levels over the preceding 3 months. It can be reported as a percentage (of total haemoglobin) or as mmol/mol (millimoles per mole). Excellent glycaemic control in a diabetic person might be around 6.5% or 48 mmol/mol.

This review was carried out by authors working with the Cochrane Oral Health and is part one of an update of a review previously published in 2010 and 2015. This review evaluates gum disease treatment versus no active treatment or usual care. Part two of the review will compare different types of periodontal treatment. We carried out this review as it is important to discover if gum disease treatment does improve glycaemic control in order to ensure best use of clinical resources. 

Study characteristics

We searched six research databases and found 35 relevant trials where people with diabetes and periodontitis were randomly allocated to an experimental group or a control group. The experimental groups received gum disease treatment called 'subgingival instrumentation', also known as scaling and root planing or deep cleaning. In some experimental groups, the deep cleaning was supplemented with instructions for cleaning teeth properly ('oral hygiene instruction'), or other gum treatments, for example, antimicrobials, which are used to treat infections. Control groups received no active treatment or 'usual care', which was oral hygiene instruction, support with oral hygiene, and/or removal of plaque above the gumline. 

The trials randomised 3249 participants in total. Almost all participants had type 2 diabetes, with a mix of good, fair, and poor diabetic control. Most of the studies were carried out in hospitals. The studies followed up participants for between 3 and 12 months.

Key results

Evidence from 30 trials (results from 2443 participants) showed that periodontitis treatment reduces blood sugar levels (measured by HbA1c) in diabetic patients on average by 0.43 percentage points (e.g. from 7.43% to 7%; 4.7 mmol/mol) 3 to 4 months after receiving the treatment compared with no active treatment or usual care. A difference of 0.30% (3.3 mmol/mol) was seen after 6 months (12 studies), and 0.50% (5.4 mmol/mol) at 12 months (one study).

There were not enough studies measuring side effects to be able to evaluate the risk of harm from gum disease treatments.

Certainty of the evidence

Most of the studies were conducted in a way that meant they were at a high risk of bias or did not provide enough information for us to make a judgement on this. However, the consistency of our findings suggests they are reliable and future research is not likely to change them. 

In summary, currently there is moderate‐certainty evidence to support gum disease treatment (known as subgingival instrumentation) for controlling blood sugar levels in people with periodontitis (gum disease) and diabetes up to 12 months after the start of the periodontal treatment.

Date of the search

The evidence is current up to 7 September 2021.

Read the full review.

Simpson TC, Clarkson JE, Worthington HV, MacDonald L, Weldon JC, Needleman I, Iheozor-Ejiofor Z, Wild SH, Qureshi A, Walker A, Patel VA, Boyers D, Twigg J. Treatment of periodontitis for glycaemic control in people with diabetes mellitus. Cochrane Database of Systematic Reviews 2022, Issue 4. Art. No.: CD004714. DOI: 10.1002/14651858.CD004714.pub4.