A recent study from the Unites States has found that some patients with stable type 2 diabetes may be having their HbA1c checked more frequently than is necessary, resulting in overtreatment.

The study cohort consisted of 31,545 patients with a mean age of 58 years and mean HbA1c 6.2%. A retrospective data analysis was carried out from commercial insurance data, between 2001 and 2013. The entry criteria were age over 18, with type 2 diabetes that had been stable, defined as an HbA1c < 7% for two consecutive tests within 24 months. Patients were excluded if they were pregnant, using insulin or subject to severe hypoglycaemia or hyperglycaemia.

Frequency of HbA1c testing was measured over 24 months from the second test confirming good control. The frequency of testing was defined as:

• Guideline recommended – once or twice a year

• Frequent – three to four times a year • Excessive – five or more times a year

Changes in treatment prescribed were ascertained within three months of each test.

In this cohort, patient testing was excessive in 6% and frequent in 55% of cases. Patients over 65 years old and those with extensive comorbidities were the most likely to have excessive testing.

Despite good glycaemic control at baseline, treatment was intensified with the addition of oral hypoglycaemic agents or insulin in 8.4% of these patients (13% of the excessively treated group, 9% of the frequent group and 7% of the tested as guidelines group). Excessive testing was associated with treatment intensification with an odds ratio (OR) 1.35 (95% CI: 1.22-1.50).

Testing frequency varied over the course of the study. Excessive testing rates remained unchanged in 2003-08 compared with 2001-02. However, excessive testing was less likely in 2009-10 and 2011.

The study was performed in the United States, where some of the pressures to test and treat are different from the NHS environment. In the UK, there is pressure to test and achieve glycaemic targets for QOF payments.

This study is a reminder to GPs that HbA1c measurements need not be repeated more than twice a year in stable patients. HbA1c targets should be set for individual patients, based on age, duration of diabetes and comorbidities.

The benefits of increasing hypo-glycaemic treatment are probably most apparent in the younger patient groups, and may be of less benefit, and possibly detrimental, in the older, stable patient.

Dr Matthew Lockyer