Estimation of serum and erythrocyte folate concentrations in the New Zealand adult population within a background of voluntary folic acid fortification.

National data on the blood folate status of New Zealand adults is lacking. The objective of this study was to describe the blood folate status and examine the predictors of blood folate status in a national sample of adults from New Zealand, a country with voluntary folic acid fortification. The 2008/09 New Zealand Adult Nutrition Survey was a nationwide multistage systematic random cross-sectional survey. Serum and erythrocyte folate concentrations were measured by microbiologic assay. The survey included 4721 participants aged ≥15 y, 3359 of whom provided a nonfasting blood sample. Biochemical folate status was measured in 3277 participants. The median serum and erythrocyte folate concentrations were 23 and 809 nmol/L, respectively. The prevalence of biochemical folate deficiency, defined as plasma folate <6.8 nmol/L or erythrocyte folate <305 nmol/L, was 2%. Having breakfast daily compared with never eating breakfast was associated with 53% higher serum and 25% higher erythrocyte folate concentrations; consumers of fortified yeast extract spread had 17% higher serum and 14% higher erythrocyte folate concentrations than nonconsumers; daily users of folate-containing supplements compared with nonusers had 48% higher serum and 28% higher erythrocyte folate concentrations. The prevalence of biochemical folate deficiency in New Zealand adults is low. Participants who ate breakfast more frequently, consumed folate-fortified yeast, or used a daily folate supplement had higher blood folate concentrations.

Ngati and healthy: translating diabetes prevention evidence into community action.

INTRODUCTION: Type 2 diabetes mellitus (T2DM) is a major health issue in New Zealand Maori. Clinical trials have demonstrated potential for the prevention of T2DM, but whether community public health programmes aiming to prevent diabetes are effective is untested. OBJECTIVE: To describe the planning and design of an intervention aiming to translate T2DM prevention clinical trial evidence into a community-wide population health intervention in a high risk predominantly Maori community. APPROACH: Community concerns about the diabetes burden were heard by the local diabetes nurse, herself a tribal member, and discussed with a locally raised academic. Project planning ensued. The intervention and its evaluation were designed using a participatory community development model. The planned intervention had three components: community-wide health promotion initiatives conveying healthy lifestyle messages, community education and monitoring for identified high-risk individuals and their extended families, and a structural strategy aimed at adapting local environments to support lifestyle changes. The evaluation plan involved interrupted time series surveys coupled with formative and process evaluations rather than a randomised control trial design. DISCUSSION: Consulting communities, validating community concerns and prioritising cultural and ethical issues were key steps. Time spent developing good relationships amongst the health provider and academic research team members at the outset proved invaluable, as the team were united in addressing the project planning and implementation challenges, such as funding obstacles that arose because of our ethically and culturally appropriate non-randomised control trial evaluation design. The pre-intervention survey demonstrated high rates of diabetes (13%), insulin resistance (33%) and risk factors, and provided evidence for positive, as opposed to negative, lifestyle intervention messages. CONCLUSION: Community-wide lifestyle interventions have the potential to reduce rates of type 2 diabetes and other chronic diseases in high-risk communities, but require a high level of commitment from the health sector and buy-in from the community. Adequate commitment, leadership, planning and resources are essential.

A spectrum of dynamic insulin sensitivity test protocols.

BACKGROUND: Numerous tests have been developed to estimate insulin sensitivity (SI). However, most of the established tests are either too expensive for widespread application or do not yield reliable results. The dynamic insulin sensitivity and secretion test (DISST) uses assays of glucose, insulin, and C-peptide from nine samples to quantify SI and endogenous insulin secretion (UN) at a comparatively low cost. The quick dynamic insulin sensitivity test has shown that the DISST SI values are robust to significant assay omissions. METHODS: Eight DISST-based variations of the nine-sample assay regimen are proposed to investigate the effects of assay omission within the DISST-based framework. SI and UN were identified using the fully-sampled DISST and data from 218 nine-sample tests undertaken in 74 female individuals with elevated diabetes risk. This same data was then used with appropriate assay omissions to identify SI and UN with the eight DISST-based assay variations. RESULTS: Median intraprocedure proportional difference between SI values from fully-sampled DISST and the DISST-based variants was in the range of -17.9 to 7.8%. Correlations were in the range of r = 0.71 to 0.92 with the highest correlations between variants with the greatest commonality with the nine-sample DISST. Metrics of UN correlated relatively well between tests when C-peptide was assayed (r = 0.72 to 1) but were sometimes not well estimated when samples were not assayed for C-peptide (r = -0.14 to 0.75). CONCLUSIONS: The DISST-based spectrum offers a series of tests with very distinct compromises of information yield, accuracy, assay cost, and clinical intensity. Thus, the spectrum of tests has the potential to enable researchers to better allocate funds by selecting an optimal test configuration for their particular application.

Economic evaluation of a community-based obesity prevention program in children: the APPLE project.

Effective strategies are urgently required to reduce the prevalence of obesity during growth. Determining which strategies are most successful should also include analysis of their relative costs. To date, few obesity prevention studies in children have reported data concerning cost-effectiveness. The aim of this study was to assess the costs and health benefits of implementing the APPLE (A Pilot Program for Lifestyle and Exercise) project, a 2-year controlled community-based obesity prevention initiative utilizing activity coordinators (ACs) in schools and nutrition promotion in New Zealand children (5-12 years). The marginal costs of the project in 2006 prices were estimated and compared with the kilograms (kg) of weight-gain prevented for children in the intervention relative to the control arm. The children's health-related quality of life (HRQoL) was also measured using the Health Utilities Index (HUI). The total project cost was NZ$357,490, or NZ$1,281 per intervention child for 2 years (NZ$1 = US$0.67 = UK pound 0.35 = EUR euro 0.52). Weight z-score was reduced by 0.18 (0.13, 0.22) units at 2 years and 0.17 (0.11, 0.23) units at 4 years in intervention relative to control children. Mean HUI values did not differ between intervention and control participants. The reduction in weight z-score observed is equivalent to 2.0 kg of weight-gain prevented at 15 years of age. The relatively simple intervention approach employed by the APPLE project was successful in significantly reducing the rate of excessive weight gain in children, with implementation costs of NZ$664-1,708 per kg of weight-gain prevented over 4 years.

Monte Carlo analysis of a new model-based method for insulin sensitivity testing.

Insulin resistance (IR), or low insulin sensitivity, is a major risk factor in the pathogenesis of type 2 diabetes and cardiovascular disease. A simple, high resolution assessment of IR would enable earlier diagnosis and more accurate monitoring of intervention effects. Current assessments are either too intensive for clinical settings (Euglycaemic Clamp, IVGTT) or have too low resolution (HOMA, fasting glucose/insulin). Based on high correlation of a model-based measure of insulin sensitivity and the clamp, a novel, clinically useful test protocol is designed with: physiological dosing, short duration (<1 h), simple protocol, low cost and high repeatability. Accuracy and repeatability are assessed with Monte Carlo analysis on a virtual clamp cohort (N=146). Insulin sensitivity as measured by this test has a coefficient of variation (CV) of CV(SI)=4.5% (90% CI: 3.8-5.7%), slightly higher than clamp ISI (CV(ISI)=3.3% (90% CI: 3.0-4.0%)) and significantly lower than HOMA (CV(HOMA)=10.0% (90% CI: 9.1-10.8%)). Correlation to glucose and unit normalised ISI is r=0.98 (90% CI: 0.97-0.98). The proposed protocol is simple, cost effective, repeatable and highly correlated to the gold-standard clamp.