Can HbA1c Replace OGTT for the Diagnosis of Diabetes Mellitus Among Chinese Patients With IFG?

March 4, 2016 updated by: The University of Hong Kong

This is a cross-sectional study that aims to assess the sensitivity and specificity of using HbA1c as a diagnostic test for detecting the presence of diabetes mellitus (DM) when compared to the use of oral glucose tolerance test (OGTT) among Hong Kong Chinese adult who have impaired fasting glucose (IFG).

The investigators will recruit around 1000 non-diabetic adult participants who have impaired fasting glucose (i.e. fasting glucose level between 5.6 to 6.9mmol/L) AND without symptoms of hyperglycaemia to undergo both HbA1c test and oral glucose tolerance test after obtaining their informed consent. A diagnosis of DM is confirmed when both the fasting glucose level and 2-hour-post challenge plasma glucose level fall into diabetic range (i.e. fasting glucose level ≥7.0mmol/L and 2-hour-post challenge plasma glucose level ≥11.1mmol/L) after a standard 75g OGTT. Participants with only 1 plasma glucose value within the diabetic range will be invited to repeat an oral glucose tolerance test for confirmation of their diagnosis as recommended by American Diabetes Association and World Health Organization. Demographic data of the participants including age, gender, smoking status, medical history, diet and activity level will be collected. Lipid profile, blood pressure, waist circumference and body mass index will be checked and the total cardiovascular risk in 10 years will be calculated for each participant using the Joint British Societies 2005 and Framingham 2008 equations to evaluate the baseline cardiovascular risk of the participants.

These data will be analyzed using SPSS. The primary outcomes are the sensitivity and specificity of HbA1c in detecting diabetes mellitus diagnosed by oral glucose tolerance test (the gold standard). A receiver operating characteristic (ROC) curve will be obtained by plotting sensitivity against (1-specificity) for each cutoff value for identification of an optimal cutoff point. Diagnostic accuracy will be assessed by the area under the curve (AUC). The differences in characteristics among participants diagnosed to have diabetes mellitus by oral glucose tolerance test or HbA1c will be compared using independent t-test or χ2 test for comparison between the 2 groups.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Detailed Description

Objectives:

  1. To calculate the sensitivity and specificity of HbA1c, using different cut-off values compared to the use of OGTT as the gold standard in the diagnosis of the presence of DM among Chinese adult patients with IFG
  2. To identify the optimal cut-off value of HbA1c for diagnosing DM among the studied population
  3. To compare the prevalence of DM among Hong Kong Chinese non-diabetic adult patients with IFG using OGTT and/or HbA1c criteria as recommended by the 2010 ADA for the diagnosis of DM
  4. To compare the characteristics (i.e. demographics, presence of risk factors for DM and cardiovascular risk) of Hong Kong Chinese patients who are diagnosed to have DM by OGTT criterion alone, HbA1c criterion alone, or both criteria

Hypotheses:

  1. The prevalence of DM is higher among Chinese adult patients with IFG compared to the general population of Hong Kong. The figure was estimated to be as much as 25% from clinical observation. The overall prevalence of DM would be even higher if both OGTT and HbA1c criteria are used.
  2. The use of HbA1c, with the cut-off threshold of ≥ 6.5% recommended by the 2010 ADA criteria for the diagnosis of DM, will pick up at least 70% of the diabetes cases identified by OGTT among this high risk group, which is superior to its use among the Chinese general population.
  3. The sensitivity of using HbA1c ≥ 6.5% for the diagnosis of DM among this high risk group is superior to the use of FG ≥ 7.0mmol/L.
  4. The optimal cut-off threshold of HbA1c in diagnosing DM for this high risk group may not be 6.5% but lower.
  5. A subset of patients with impaired glucose regulation (IFG +/- IGT) will be identified as diabetic according to the HbA1c criterion alone. This group of patient may have a different cardiovascular risk profile compared to the group of patients who are diagnosed to have DM according to plasma glucose criteria alone.

Methods:

Research Design:

This is a cross-sectional diagnostic test study to be carried out at various general out-patient clinics (GOPCs) across Hong Kong.

Target population and Sampling method:

Around 1000 Chinese adult subjects who are classified to have IFG will be recruited from various GOPCs from the Hong Kong West Cluster and New Territories East Cluster. Convenience sampling will be employed.

Sample Size Calculation In this diagnostic test study, the sample size calculation was considered using the disease prevalence and test characteristics represented by the sensitivity and specificity of HbA1c to diagnose DM. The use of HbA1c is assumed to have an expected sensitivity and specificity of 80%, an approximate estimate according to previous studies, compared to OGTT for the diagnosis of DM among subjects with IFG and/or IGT. With an estimated prevalence of DM of 25% in the high risk Chinese population in Hong Kong based on epidemiological survey in the Chinese population with similar risk profiles, a sample of 204 subjects with DM and 612 subjects without DM will be recruited to obtain the lower limit of the 95% confidence interval greater than 0.7 with a probability of 0.9530. A sample of 816 will be required. To account for 20% attrition rate, a total sample of 1020 will be required, with 255 subjects with DM and 765 subjects without DM.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
1357

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Hong Kong
      • Hong Kong, Hong Kong, 852
        • Tsan Yuk Hospital RAMP Clinic
      • Hong Kong, Hong Kong
        • Ap Lei Chau General Out-patient Clinic
      • Hong Kong, Hong Kong
        • Lek Yuen General Out-Patient Clinic

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Sampling Method

Probability Sample

Study Population

Chinese adult subjects who are classified to have IFG will be recruited from various GOPCs from the Hong Kong West Cluster and New Territories East Cluster.

Description

Inclusion Criteria:

  • Aged ≥ 18 year
  • Chinese ethnicity
  • Diagnosis of impaired fasting glucose (i.e. FG between 5.6-6.9mmol/L) identified from latest blood test results within 18 months prior to recruitment)

Exclusion Criteria:

  • Known history of diabetes mellitus or on hypoglycaemic treatment
  • Having symptoms of hyperglycaemia at recruitment
  • Women who are pregnant or breast-feeding at recruitment
  • Patients taking glucocorticoid at recruitment
  • Active and uncontrolled thyroid diseases (including subjects on thyroid replacement therapy or anti-thyroid drugs) or active endocrine diseases such as Cushing's syndrome or Acromegaly at recruitment
  • Clinically significant anaemia at recruitment
  • Severe renal impairment i.e. eGFR ≤ 30 ml/min/1.73m2
  • History of blood donation or blood transfusion within 3 months prior to recruitment

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
The sensitivity of the use of HbA1c
Time Frame: around 12-16 weeks after the study completed
The sensitivity of the use of HbA1c at different cut points for diagnosing DM among Chinese adult patients with IFG compared to OGTT as the gold standard.
around 12-16 weeks after the study completed
The specificity of the use of HbA1c
Time Frame: around 12-16 weeks after the study completed
The specificity of the use of HbA1c at different cut points for diagnosing DM among Chinese adult patients with IFG compared to OGTT as the gold standard.
around 12-16 weeks after the study completed

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
The optimal cut-off level of HbA1c
Time Frame: around 12-16 weeks after the study completed
The optimal cut-off level of HbA1c for diagnosing DM among Chinese adult patients with IFG
around 12-16 weeks after the study completed
OGTT criteria in Chinese
Time Frame: around 12-16 weeks after the study completed
The prevalence of DM among Chinese adult patients with IFG defined by OGTT criteria
around 12-16 weeks after the study completed
HbA1c criteria in Chinese
Time Frame: around 12-16 weeks after the study completed
The prevalence of DM among Chinese adult patients with IFG defined by HbA1c criteria
around 12-16 weeks after the study completed
Cardiovascular risk
Time Frame: around 24-48 weeks after the study completed
Difference in cardiovascular risk between patients who are diagnosed to have DM by HbA1c criteria compared to OGTT criteria
around 24-48 weeks after the study completed
DM risk
Time Frame: around 24-48 weeks after the study completed
Difference in DM risk between patients who are diagnosed to have DM by HbA1c criteria compared to OGTT criteria
around 24-48 weeks after the study completed

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
The University of Hong Kong

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Chinese University of Hong Kong

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: YU YT Esther, Doctor, Department of Family Medicine and Primary Care, The University of Hong Kong

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

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Study Major Dates

Study Start

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
May 1, 2013

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
March 1, 2015

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
March 1, 2015

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
April 23, 2015

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
May 6, 2015

First Posted (Estimate)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
May 12, 2015

Study Record Updates

Last Update Posted (Estimate)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
March 7, 2016

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 4, 2016

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
March 1, 2016

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • UW 13-299

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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