Ethnic differences in the prevalence of new and known diabetes mellitus, impaired glucose tolerance, and impaired fasting glucose. Diabetes Heart and Health Survey (DHAH) 2002-2003, Auckland New Zealand.

AIM

To estimate the prevalence of new and known diabetes mellitus, impaired glucose tolerance (IGT), and impaired fasting glucose (IFG) by ethnic group in Auckland.

METHODS

The Diabetes Heart and Health Survey (DHAH) was a cross-sectional population based survey and was carried out in Auckland between January 2002 and December 2003, inclusive. Participants answered a self-administered questionnaire to assess whether they had previously diagnosed diabetes. Those participants who were not previously diagnosed with diabetes were then given a glucose tolerance test (GTT) to determine diabetes status.

RESULTS

Of the total sample 6.7% were previously diagnosed (known) with type 2 diabetes, and a further 2.6% were newly diagnosed. Within the ethnic groups Europeans had the lowest level of both new and known diabetes followed by Maori and then Pacific people (mostly of Samoan, Tongan, Niuean, or Cook Islands origin). The proportions of new/known diabetes by ethnicity were 1.8%/3.9% for Europeans, 3.8%/12.0% for Maori, and 4.0%/19.5% for Pacific. Only Pacific were found to have a significantly greater relative risk (RR) than Europeans of being newly diagnosed with diabetes, particularly in the <45 (RR 11.6), and 45-54 year (RR 4.2) age groups. Compared to Europeans, Maori had a significantly greater risk of known diabetes in the 45-54 (RR 6.4) and 55-64 (RR 4.1) year age groups, while Pacific had a significantly greater risk in all age groups which ranged from RR 2.5 in those aged 65+ to RR 9.3 in the 55-64 year age group. For Europeans and Maori, the greatest proportions of diabetes occurred in the 65+ year age group, however for Pacific this occurred in the 55-64 year age group. IFG levels were only found to be significantly different from Europeans in Maori aged 45-54, and Pacific aged 45-54 and <45 years. IGT levels were only found to be significantly different from Europeans in Pacific aged 45-54 years.

CONCLUSIONS

The prevalence of diabetes was 2.8 times greater for Maori, and 4.1 times greater for Pacific compared with Europeans. However for every two European people with previously diagnosed diabetes there was approximately one (0.92) person in the community undiagnosed while for every three Maori people with diagnosed diabetes was one Maori person undiagnosed. For every five Pacific with diagnosed diabetes there was just over one (1.1) Pacific person undiagnosed.