Search strategy and study selection
A search strategy was developed using the population, intervention, comparison, outcomes (PICO) approach to address the review question “What is the diagnostic yield of PoC screening for T2DM in the dental setting?”
A MEDLINE – PubMed, EMBASE, Web of Science and the Cochrane Library search, limited to the English language, was performed with no time specification. A comprehensive search strategy, including qualified Medical Subject Headings (MeSH Terms) and keywords or free text words in simple or multiple conjunctions using Boolean operator (AND/ OR) was conducted. Search terms were grouped into categories for “Problem”, “Intervention” and “Outcome.”
MEDLINE – PubMed search strategy
(((((((((((adult onset diabetes mellitus[MeSH Terms]) OR hyperglycemia[MeSH Terms]) OR prediabetes[MeSH Terms]) OR diabetic) OR undiagnosed) AND Humans[MeSH] AND adult[MeSH])) NOT gestational diabetes[MeSH Terms]) AND Humans[MeSH] AND adult[MeSH])) AND ((((dental auxiliaries[MeSH Terms]) OR (dentist* or dental)) OR periodont*) OR "oral health professional*")) AND (((((screen*) OR hba1[MeSH Terms]) OR blood glucose[MeSH Terms]) OR identif*[MeSH Terms]) OR point of care)
OVID - EMBASE search strategy
- (Diabetes or pre-diabetes or hyperglycemia*).
- (screen* or examin* or identif* or "point-of-care")
- (adult* or patient* or individuals* or people*)
Outcome measures
To estimate the proportion of adult dental patients with undiagnosed T2DM or pre-diabetes (hyperglycaemia).
Study and participant selection
Studies were eligible for inclusion if
- they were cross-sectional in design and used PoC screening for undiagnosed DM or hyperglycaemia in the dental setting. This includes studies that used blood glucose investigation and Glycated haemoglobin (HbA1c).
- the results of the PoC screening test were confirmed with the reference test (diagnostic test). The reference test includes all currently available criteria and methods recommended by the WHO or American Diabetes Association (ADA) for the diagnosis of DM or hyperglycaemia that is not suggestive of DM.
Studies were excluded if
- they used PoC screening based on reagent strips that rely on colour-coding.
- they relied on PoC HbA1c for diagnosis, as the current WHO and ADA guidelines do not recommend point-of-care HbA1c for diagnostic purposes[25, 26].
Participant’s inclusion criteria
Adult patients accessing dental care for routine dental treatment, who had never been told by a healthcare provider that they have DM or hyperglycaemia.
Participants exclusion criteria
Patient with previous diagnosis of DM or pre-diabetes
Unable to provide consent
Severe physical or mental impairment
Serious heart or renal disorder
Data Extraction and Quality Assessment
Two reviewers extracted information from selected papers on author, country, year, number of participants with undiagnosed T2DM or hyperglycaemia, age, eligibility criteria, exclusion criteria, gender distribution, type of PoC screening, and diagnostic test and the threshold used. Any discrepancy or missing information was discussed, and a consensus reached between the authors. Studies that met the criteria (Table 1) were used to categorize patient into one of three categories: a) normoglycemia b) pre-diabetes and c) DM[25, 26]. The screening test includes all PoC devices for measuring blood glucose or HbA1c, and the diagnostic tests include laboratory HbA1c, Oral Glucose Tolerance Test (OGTT) and fasting plasma glucose (FPG).
A systematic review[27] concluded with no consensus reached on the tools to assess the quality of observational study methodology investigating prevalence. Further, the Cochrane collaboration recommends a domain-based evaluation to assess the risk of bias on a subjective basis[28]. Hence, we chose the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool[29] for observational studies to perform the quality assessment. QUADAS- 2 comprises four domains: patient selection, index test, reference standard and flow of patients and timing. Individual articles were assessed against each domain to identify the risk of bias.
Table 1
Diagnostic criteria for DM and hyperglycaemia adopted by the WHO and ADA
Diabetes | |
FPG | ≥ 7.0 mmol/L (126 mg/dl) or |
2-hour OGTT | ≥ 11.1 mmol/L (200 mg/dl) or |
HbA1c | ≥ 6.5% |
Hyperglycaemia (Pre-diabetes range) | |
Impaired glucose tolerance (IGT) | |
FPG | < 7.0 mmol/L (126 mg/dl) |
2-hour OGTT | ≥ 7.8 and < 11.1 mmol/L (140 mg/dl and 200 mg/dl) |
Impaired fasting glucose (IFG) | |
Fasting plasma glucose | 6.1 to 6.9 mmol/L (110 mg/dl to 125 mg/dl) |
2-hour OGTT | < 7.8 mmol/L (140 mg/dl) |
HbA1c* | A1C ≥ 5.7 to 6.4% (39–47 mmol/mol) |
* Criteria recommended by American Diabetes Association alone, FPG fasting plasma glucose; OGTT oral glucose tolerance test; HbA1c glycated haemoglobin; IFG impaired fasting glucose; IGT impaired glucose tolerance |
Data synthesis and analysis
Meta-analysis was performed to calculate the weighted prevalence and presented in forest plots or table with 95% confidence intervals (CI). The screening test used blood glucose investigation and glycated haemoglobin that differed significantly in their threshold. To avoid variation in the PoC screening, a subgroup analysis was conducted for the RBG and HbA1c test. For the diagnostic test, no subgroup analysis was done since the diagnosis is based on the criteria adopted by the WHO and ADA.
The PoC test results were grouped into low (normoglycemic range) and high risk (hyperglycaemic range). The diagnostic test results were categorized into pre-diabetes and T2DM based on the reported values. To identify the proportion of dental patients with undiagnosed T2DM or hyperglycaemia, a Freeman-Tukey transformation - arcsine square root transformation[30] was used to calculate the weighted summary proportion under the random-effects model[31]. Heterogeneity among studies was reported using the I2 statistic. All analyses were performed using MedCalc 12.1.4.0 statistical software (MedCalc Software, Mariakerke, Belgium).
Role of the funding source
No funding was allotted for the conduct of this review.