New US guidance: HbA1c targets for glycaemic control in type 2 diabetes.

The American College of Physicians has issued updated guidance on the use of haemoglobin-A1c (HbA1c) levels in monitoring glycaemic control of patients with type 2 diabetes.

It is accepted that good glycaemic control is necessary in diabetes and if achieved will significantly reduce the likelihood of adverse complications. HbA1c is widely used as a means of monitoring diabetic control, and this paper is intended to summarise the evidence base for monitoring and for suitable HbA1c levels in particular. As there are already many guidelines available on this topic, the College considered that it was appropriate to provide a rigorous review of suitable existing guidelines rather than produce a new guideline from first principles.
A comprehensive search strategy was used to locate guidelines that included discussion of diabetic control. Eligibility was restricted to English language because of the difficulties in translating non-English documents, and only most recent updates were used. Eligible guidelines were assessed using the Appraisal of Guidelines, Research and Evaluation in Europe (AGREE) collaboration method to get an assessment of guideline quality. Recommendations on glycaemic control were extracted from high quality guidelines and used to synthesise overall recommendations.

Nine sets of guidelines were accepted as being of sufficient quality and included specific recommendations on control. Based on these, the authors recommend the following (taken directly from the article summary with Anglicisation of spellings):

• Statement 1: To prevent microvascular complications of diabetes, the goal for glycaemic control should be as low as is feasible without undue risk for adverse events or an unacceptable burden on patients. Treatment goals should be based on a discussion of the benefits and harms of specific levels of glycaemic control with the patient. A haemoglobin A1c level less than 7% based on individualized assessment is a reasonable goal for many but not all patients.
• Statement 2: The goal for haemoglobin A1c level should be based on individualized assessment of risk for complications from diabetes, comorbidity, life expectancy, and patient preferences.
• Statement 3: We recommend further research to assess the optimal level of glycaemic control, particularly in the presence of comorbid conditions.

The authors comment that there are still challenges in understanding the benefits and harms of particular levels of control, especially in complex patients, and further research would be valuable. Attention should also be paid to control of blood pressure and lipid levels.

Ann Intern Med 2007; 147: 417-22