What is hba1c measured in

If you are an adult with medication that does cause hypoglycaemia i. Talk to your Healthcare Professional about the right goal for you. The calculation below is provided to illustrate the relationship between HbA1c and average blood glucose levels. This calculation is not meant to replace an actual lab HbA1c result, but to help you better understand the relationship between your test results and your HbA1c.

Use this information to become more familiar with the relationship between average blood glucose levels and HbA1c. It should not replace the HbA1c check carried out by your doctor and the result shown here may differ from the lab value you get. This calculation should not be used to make therapy decisions or changes. You can discuss with your healthcare professional how this approximate measurement could help you in your overall diabetes management.

The HbA1c is important, but it's not a substitute for structured self-monitoring. Only regular blood glucose checks show you how meals, activity, medications and stress affect your blood glucose at a single moment in time, as well as over the course of a day or week. Without regular self-checking to provide day-to-day insights, an HbA1c result can be confusing. Because it gives an average view, a person with frequent highs and lows could have an in-range result that is the same as someone with blood glucose consistently in target range.

This animation shows two examples of blood glucose variability where the HbA1c would be the same. This is why self-monitoring blood glucose levels is valuable. Remember one blood glucose check in isolation will not tell you the whole story. Getting the results is one thing, but knowing what to do with them is key. Making the most of your data can help you to make better decisions, about your health, such as dietary choices and insulin doses.

Some centres may have had more unreliable local measurement methods than others or there may have been more errors with data entry.

The time-lag between blood sampling and analysis at the central laboratory was not associated with levels of agreement, suggesting that there were no issues affecting measurement related to storage and transport of blood samples. Discrepancies between HbA1c measurements can sometimes be explained by issues with instrumentation lot-to-lot variation with HbA1c cartridges; variation between instrumentation makes and models; differences in sample collection devices; measurement errors by users; rogue cartridges within a batch.

This study does not provide evidence that central measurements are more accurate or more reliable, but rather that the measurement of HbA1c is variable between methods of analysis. In the routine practice of diabetes care, local measurement at clinics incurs lower costs and is convenient for decision-making; in the clinical trial setting, however, a single systematic centralised methodology would be preferable to eliminate any chance that differences in measurement methodology, or levels of training, affect the estimation of effect sizes.

Pragmatically, this study provides no reason why local measurements could not be used in place of missing central measurements, given that there would be no overall bias incurred. This study shows that a central laboratory provides a standardised measurement methodology for recording HbA1c during follow-up, and that the results obtained are an unbiased representation of HbA1c measured locally at trial centres.

Overall, the mean and standard deviation of measurements were similar for both sources of measurement, meaning that power calculations would not be affected by choice of source of measurement.

However, there was found to be a wide spread of differences between local and central measurements for individual blood samples. This means that in some cases, post-diagnosis decision-making could be quite different if based on local measurements compared with central ones. For the purposes of developing the SCIPI analysis plan the primary analysis will use central laboratory measures where available and use local results when this is not the case. This is based on the lack of systematic bias and the consistency in the size of the means and SDs across time points and scales.

Future investigators, and those using measures of HbA1c as indicators of standards of routine clinical care need to be aware of the variability that persists in the measurement of HbA1c across centres within the United Kingdom, despite a commitment to working according to the IFCC initiative for standardisation of measuring and reporting HbA1c.

A single central laboratory provides a uniform methodology that, whilst more expensive, removes some of the complexity of sources of variation inherent in the multicentre local measurement approach.

SCIPI: Randomised controlled trial of continuous subcutaneous insulin infusion compared to multiple daily injection regimens in children and young people at diagnosis of type I diabetes mellitus. General Medical Services Contract. Quality and Outcomes Framework Statistics for Wales, — IDF Diabetes atlas, 7th ed. Estimating the current and future costs of type 1 and type 2 diabetes in the UK, including direct health costs and indirect societal and productivity costs.

Diabet Med. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med. Article Google Scholar. A1C variability and the risk of microvascular complications in type 1 diabetes: data from the Diabetes Control and Complications Trial. Diabetes Care. Clin Chem Lab Med. Study protocol for a randomised controlled trial of insulin delivery by continuous subcutaneous infusion compared to multiple daily injections.

Download references. All authors read and approved the final manuscript. AM helped with data issues and reviewed the manuscript. JWG reviewed the manuscript. PN contributed the biochemistry methodology and reviewed the manuscript. CG raised the original question and led the statistical team contributing to the statistical analysis plan, analyses and manuscript. All participants gave informed consent prior to enrolment in the study.

Barbara N. You can also search for this author in PubMed Google Scholar. Correspondence to Barbara N. Reprints and Permissions. Arch, B. Measurement of HbA1c in multicentre diabetes trials — should blood samples be tested locally or sent to a central laboratory: an agreement analysis.

Trials 17, Download citation. Received : 30 June Accepted : 04 October Published : 24 October Anyone you share the following link with will be able to read this content:. Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative.

Skip to main content. Search all BMC articles Search. Download PDF. Research Open Access Published: 24 October Measurement of HbA1c in multicentre diabetes trials — should blood samples be tested locally or sent to a central laboratory: an agreement analysis Barbara N. Abstract Background Glycated haemoglobin HbA1c is an important outcome measure in diabetes clinical trials. Results Five hundred and ninety pairs of measurement, representing children and 15 trial centres across four follow-up time points, were compared.

Conclusions Variation in agreement between HbA1c measurements was greater than had been expected although no overall bias was detected and standard deviations were similar. Trial registration Eudract No. Background In , approximately 3. Methods At the time of this agreement analysis children and young people aged 7 months to 15 years, who had been newly diagnosed with type I diabetes mellitus, had been randomised in a ratio to receive either continuous subcutaneous insulin infusion CSII or multiple daily injections MDI of insulin.

Quality assurance of the measurement of HbA1c Portable instrumentation is calibrated regularly with local laboratories. Results Sample characteristics Of children randomised for the trial, had at least one pair of measurements of HbA1c included in this analysis see below and Fig. Your results may mean something different. If you have questions about your results, talk to your health care provider.

Your health care provider may have other recommendations for you, depending on your overall health, age, weight, and other factors. Learn more about laboratory tests, reference ranges, and understanding results. The HbA1c test is not used for gestational diabetes , a type of diabetes that only affects pregnant women, or for diagnosing diabetes in children.

Also, if you have anemia or another type of blood disorder , an HbA1c test may be less accurate for diagnosing diabetes. If you have one of these disorders and are at risk for diabetes, your health care provider may recommend different tests. The information on this site should not be used as a substitute for professional medical care or advice.

Contact a health care provider if you have questions about your health. What is a hemoglobin A1c HbA1c test? Other names: HbA1c, A1c, glycohemoglobin, glycated hemoglobin, glycosylated hemoglobin. What is it used for?

If you already have diabetes, an HbA1c test can help monitor your condition and glucose levels. Why do I need an HbA1c test? If you are under 45, you may need this test if you have certain risk factors.

These include: Being overweight or obese High blood pressure History of heart disease Physical inactivity Testing should be done every 3 years, and more frequently if your results show you have prediabetes. You may also need an HbA1c test if you have symptoms of diabetes. These include: Increased thirst Increased urination Blurred vision Fatigue.