Diabetes Management News and Views

The 46th Annual Meeting of the European Association for the Study of Diabetes took place 20th – 24th September in Stockholm, Sweden. Presentations at the meeting included ‘WHO new diagnostic criteria 2010′ and several short presentations on ‘HbA1c for diabetes mellitus diagnosis: need for reassessment’.

As a measure of glycaemia, HbA1c is less variable within and between individuals than measures of acute glucose control
Rohlfing et al.Clin Chem 2002;48:1116

The WHO Guidelines on What Diagnostic Tests Should be Used to Define Glycaemic Status are now about ten years old. Since their publication, the HbA1c test has been standardised – >99% of assays in US and Europe are standardised by the NGSP program to the DCCT standard.

Type 2 diabetes onset can be subtle, without symptoms and without a clear separation of glucose values from the non-diabetic distribution. Glucose levels fluctuate extensively within the day and between days, and also in response to stress.

“There is no clear division between diabetics and non-diabetics in their FPG (fasting plasma glucose) concentration or their response to an oral load.”
National Diabetes Data Group, Diabetes 1979;28: 1039-57

The WHO Guidelines on What Diagnostic Tests Should be Used to Define Glycaemic Status show that fasting plasma glucose will fail to diagnose approximately 30% of people with diabetes.

The WHO Guidelines on What Diagnostic Tests Should be Used to Define Glycaemic Status state:

Glucose should be measured immediately after collection by near patient testing, or if a blood sample is collected, plasma should be separated immediately, or the sample should be collected into a container wih glycolytic inhibitors (e.g. NaF) and placed on ice-water until separated prior to analysis.

The NHS document Putting Prevention First states, in the section on diabetes risk assessment, that either a fasting plasma glucose (FPG) or an HbA1c test can be used to identify those at high risk of developing or having diabetes.

A unique longitudinal study was published in the New England Journal of Medicine earlier this year about the advantages of HbA1c over fasting glucose.

Samples containing variant haemoglobin can cause erroneous results in the measurement of HbA1c, with different test systems often giving different results. This means that many labs have to send these samples to a reference lab for accurate analysis, which is expensive, inconvenient and time consuming. So what’s the answer?