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HbA1c levels naturally higher in black patients

By Mark Pownall

HbA1c levels are higher in black people compared to Caucasians, and GPs should take this into account when predicting the risk of diabetes complications, US researchers argue.

A study of 1581 non-Hispanic black and white participants between 18 and 87 years of age without known diabetes and 1967 Hispanic black and white participants older than 40 years without known diabetes found HbA1c levels were 0.13 percentage points higher in black than in white participants with normal glucose tolerance and 0.47 percentage points higher after adjustment for plasma glucose levels. The difference became larger as glucose tolerance worsened.

The mechanism for the difference is unknown, but study leader Dr David Ziemer, an endocrinologist at Emory University, Atlanta advised: ‘The limitations of HbA1c measurements indicate that additional measurements of glycaemic control should be included in clinical decision making.

‘Greater emphasis on home glucose-monitoring data may be helpful, and clinicians should not limit their assessment of glycaemic control in their patients to measuring HbA1c levels.'

Ann Intern Med 2010;152:770-777


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