Diabetes and hyperglycaemia among patients with myocardial infarction in a multiethnic population

Mortality in individuals with Type 2 diabetes and heart disease in a unique New Zealand population

AIMS

To determine rate and predictors of mortality in patients with Type 2 diabetes living in a population with a large proportion of Maori and Pacific peoples who were admitted to hospital with myocardial infarction (MI) or congestive cardiac failure (CCF).

METHODS

The study population included 4193 individuals with Type 2 diabetes who lived in South Auckland and who participated in a primary care audit between 1994 and 1999. We studied a subgroup of 319 patients who subsequently had a hospital admission for MI or CCF between 1999 and 2001. We examined their demographics, drug treatment, vascular risk factors and mortality up to 2003.

RESULTS

Following discharge, the prescription of beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, aspirin and statins had all increased significantly. Vascular risk factors including total cholesterol, high-density lipoprotein (HDL) cholesterol, systolic blood pressure and glycated haemoglobin (HbA(1c)) improved significantly. Nevertheless, mortality remained high with individuals admitted because of an MI 7.2-fold more likely to die early and those with a CCF admission 5.9-fold more likely to die early than other individuals with Type 2 diabetes. Maori patients have an 80% excess mortality.

CONCLUSIONS

Patients with past admission for MI and/or CCF remain at exceptionally high risk of death for at least 4 years after hospital admission, even with improvements in management of cardiovascular risk factors. Maori individuals are at particular risk.

Diabetes in New Zealand

While the ethnic make up of the New Zealand population is predominantly European, the Polynesian population, consisting of indigenous New Zealand Maori and more recent immigrants from the other Pacific Islands is increasing rapidly. The prevalence of diabetes in these Polynesians is high. There is also an increasing prevalence of obesity, and obesity is a greater problem amongst Polynesian people. The number of elderly people in the population is increasing. All of these demographic changes are increasing the incidence and prevalence of Type 2 diabetes. The incidence of Type 1 diabetes is also rising, although the reasons for this are unknown. Diabetic nephropathy is the most common cause of end stage renal failure in New Zealand. Polynesian people with diabetes, and in particular Maori, have a very high rate of diabetic nephropathy and develop renal failure at a more rapid rate than European patients with nephropathy relating to Type 1 diabetes. The propensity for Maori patients with Type 2 diabetes to develop renal failure may relate to a younger age at the onset of diabetes, a genetic susceptibility to nephropathy, and socio-economic or cultural factors leading to less adequate medical care.

Screening for gestational diabetes mellitus in a multiethnic population in New Zealand

We have compared the characteristics of those screened and unscreened for gestational diabetes mellitus (GDM) in a multiethnic population in New Zealand. All obstetric records for a 12-month period were reviewed manually and electronically. Pre-gestational diabetes status, screening for GDM and obstetric history were recorded. Data for 4885 singleton pregnancies, uncomplicated by known pre-existing diabetes were available. Overall 50.6% of women were screened for GDM using a glucose challenge test, ranging between 36.8% among Europeans to 68.5% among Pacific Islanders (P<0. 001). Attendance at a follow up oral glucose tolerance test among those with a positive screen was 77.4%, with no ethnic difference. Rates of GDM were 3.3, 7.9 and 8.1% for Europeans, Maori and Pacific Islanders. An estimated 45-72% of women with GDM went undetected. Although increasing weight was associated with an increased likelihood of screening, 44.9, 34.8 and 21.1% of obese (weight 85+kg) Europeans, Maori and Pacific Islanders, respectively, were not screened. Increasing age was not associated with increased screening. Screening for GDM is not occurring even in those with clear and agreed indications for selective screening. We hypothesise that the current debate over criteria for selective screening may be undermining screening for those most at risk.