HbA1c screening for undiagnosed diabetes in New Zealand

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Abstract
Objectives To describe a screening programme to detect undiagnosed diabetes in high‐risk ethnic groups in New Zealand and determine the specificity and sensitivity of HbA1c to detect fasting hyperglycaemia. Research design and methods HbA1c was offered to subjects over 20 years of age participating in a screening programme for hepatitis B that was targeted at non‐European populations. Two hundred and forty‐four predominantly Maori subjects, with HbA1c levels 5 to 7.9% and who were not known to have diabetes, were tested with an oral glucose tolerance test. Comparison was made with fasting and 2‐h samples. Results Fifty thousand eight hundred and nineteen subjects were screened using HbA1c. 12% had HbA1c levels of 6.1% or more, and in 4% of the population HbA1c was 7.1% or more. Maori, Pacific Island people, and Indians had particularly high rates of elevated HbA1c. HbA1c levels of 6.1% and greater were 94% sensitive and 77% specific in detecting the 32 subjects who had a fasting glucose of 7.0 mmol/L or more, and 90% sensitive and 73% specific for 20 subjects with a 2‐h glucose of 11.1 mmol/L or more. Conclusions Rates of elevated HbA1c levels in non‐Europeans in New Zealand are very high, particularly in Maori, Pacific Island Peoples', and Indians, reflecting their high risk of diabetes and vascular disease. HbA1c can be used as an opportunistic screening test for diabetes and glucose intolerance, but a high level should be followed by an oral glucose tolerance test. Copyright © 2004 John Wiley & Sons, Ltd.