Type 2 diabetes HbA1c monitoring ‘may be over-frequent’

Monitoring may be too frequent
Published on Thursday, 01 November 2012 14:50
Written by Scott Buckler

Current six-monthly monitoring of HbA1c among some patients with type 2 diabetes may be too frequent and cause unnecessary treatment changes, according to a new study 'Optimal prescribing of glucose lowering therapy for patients with type 2 diabetes' (PDF1MB), released today by NHS Diabetes and the Department of Primary Care Health Sciences, University of Oxford

Using data from the Diabetes Glycaemic Education and Monitoring (DiGEM) study, the research found three-monthly monitoring was likely to produce a high rate of 'false' positive results, while six-monthly monitoring would only be justified in those already close to the treatment threshold.

Annual monitoring, however, was likely to give the most accurate results, with the majority of results above the threshold, reflecting a true change in blood glucose control in all patients. Current NICE guidelines recommend six-monthly testing of HbA1c, but the researchers conclude their findings may give more support to the less frequent testing applied in QOF.

"In the context of the wider project, false-positive tests correspond to the potential for prescribing decisions, such as a dose increase or an additional medication, being made in response to a chance finding rather than a true change", explained lead researcher Professor Andrew Farmer.

Using data from the General Practice Research Database on 100,000 people with type 2 diabetes in UK general practice between 1989 and 2011, the study also investigated the HbA1c-lowering effects of metformin and sulfonylureas in routine general practice. The researchers found higher doses of metformin to be more effective at lowering HbA1c than lower doses, but that the difference between doses is small compared to the main effect of metformin. For sulfonylureas they found no evidence for a greater effect at higher doses.

Professor Farmer concluded: "These findings provide a valuable insight that may guide our expectations about response when starting glucose lowering medication. They provide us with information about average response and variation around that. In addition, the response will be affected by adherence to medication and lifestyle factors."

Source: ©NHS Diabetes

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