High impact of nephropathy on five-year mortality rates among patients with Type 2 diabetes mellitus from a multi-ethnic population in New Zealand

Abstract

Aims: Type 2 diabetes mellitus and its complications are common among Polynesians in New Zealand. This study investigated the mortality from diabetes among indigenous Maori and recent migrants from the South Pacific.

Methods: Death certificates and other reports were collected to enumerate those who had died in an across-community cohort study of 765 diabetic patients aged 40-79 years in 1991. Five year mortality status was ascertained in 99.7% and death certificates were obtained from 129 (88%) of the 146 who had died. Diabetes was missed from 36% of death certificates.

Results: Compared to Europeans with Type 2 diabetes, Maori with Type 2 diabetes were 2.66 (1.63-4.35) fold as likely to die from diabetes-related conditions, including a 13.1 (3.7-46.4) fold greater risk of death from nephropathy. Pacific Islands Polynesians with Type 2 diabetes had a similar mortality to Europeans with Type 2 diabetes (hazards ratio 1.06 (0.68-1.65)). After 6 years, 10.7 (2.2-19.3)% more Maori had died than Pacific Islands Polynesians.

Conclusions: Maori with Type 2 diabetes are dying from diabetic complications, particularly nephropathy, at an alarming rate. The magnitude of the difference between Maori and Pacific Islands Polynesians suggests environmental rather than inherited factors are involved and these need further investigation.