The broader health benefits of optimised dietary thresholds proposed for type 2 diabetes prevention in Aotearoa New Zealand: simulation modelling.

AIM: Optimised dietary thresholds for type 2 diabetes prevention exist; however, they likely have additional benefits beyond diabetes prevention. We have modelled the effects of the proposed dietary thresholds on Health-Adjusted Life Years (HALY), health inequities and health system cost in Aotearoa New Zealand. METHODS: We created a national diet scenario using the optimised thresholds and compared it with current intakes using an established multistate life table. The primary model considered change in outcome from increasing intakes of fruits, vegetables, nuts and seeds while decreasing red meat and sugar-sweetened beverages. A separate secondary nutrient-based model considered change due to increasing whole grains and yoghurt while decreasing refined grains, potatoes and fruit juice. Both models considered the direct non-weight mediated associations between diet and disease. RESULTS: In the primary model, adopting the dietary thresholds produced clear benefit to Aotearoa New Zealand in terms of HALY (1.2 million years [95%UI 1.0-1.5]), and a health system cost saving of $17.9 billion (95%UI 13.6-23.2) over the population life course. HALY gain was at least 1.8 times higher for Maori than non-Maori. The secondary model indicated further gains in HALY for all population groups and health systems costs. CONCLUSION: These striking benefits of altering current dietary intakes provide strong evidence of the need for change. Such change requires government commitment to an overarching food strategy in Aotearoa New Zealand to build supportive food environments that enable healthy choices at affordable prices.

Teaching people to eat according to appetite - Does the method of glucose measurement matter?

BACKGROUND: Hunger training teaches people to eat according to their appetite using pre-prandial glucose measurement. Previous hunger training interventions used fingerprick blood glucose, however continuous glucose monitoring (CGM) offers a painless and convenient form of glucose monitoring. The aim of this randomised feasibility trial was to compare hunger training using CGM with fingerprick glucose monitoring in terms of adherence to the protocol, acceptability, weight, body composition, HbA1c, psychosocial variables, and the relationship between adherence measures and weight loss. METHODS: 40 adults with obesity were randomised to either fingerpricking or scanning with a CGM and followed identical interventions for 6 months, which included 1 month of only eating when glucose was under their individualised glucose cut-off. For months 2-6 participants relied on their sensations of hunger to guide their eating and filled in a booklet. RESULTS: 90% of the fingerpricking group and 85% of the scanning group completed the study. Those using the scanner measured their glucose an extra 1.9 times per day (95% CI 0.9, 2.8, p < 0.001) compared with those testing by fingerprick. Both groups lost similar amounts of weight over 6 months (on average 4 kg), were satisfied with the hunger training program and wanted to measure their glucose again within the next year. There were no differences between groups in terms of intervention acceptability, weight, body composition, HbA1c, eating behaviours, or psychological health. Frequency of glucose testing and booklet entry both predicted a clinically meaningful amount of weight loss. CONCLUSIONS: Either method of measuring glucose is effective for learning to eat according to hunger using the hunger training program. As scanning with a CGM encouraged better adherence to the protocol without sacrificing outcome results, future interventions should consider using this new technology in hunger training programs.

Quantity versus quality of objectively measured sleep in relation to body mass index in children: cross-sectional and longitudinal analyses.

BACKGROUND/OBJECTIVES: Although sleep duration is well established as a risk factor for child obesity, how measures of sleep quality relate to body size is less certain. The aim of this study was to determine how objectively measured sleep duration, sleep timing, and sleep quality were related to body mass index (BMI) cross-sectionally and longitudinally in school-aged children. SUBJECTS/METHODS: All measures were obtained at baseline, 12 and 24 months in 823 children (51% female, 53% European, 18% Maori, 12% Pacific, 9% Asian) aged 6-10 years at baseline. Sleep duration, timing, and quality were measured using actigraphy over 7 days, height and weight were measured using standard techniques, and parents completed questionnaires on demographics (baseline only), dietary intake, and television usage. Data were analysed using imputation; mixed models, with random effects for person and age, estimated both a cross-sectional effect and a longitudinal effect on BMI z-score, adjusted for multiple confounders. RESULTS: The estimate of the effect on BMI z-score for each additional hour of sleep was -0.22 (95% CI: -0.33, -0.11) in cross-sectional analyses and -0.05 (-0.10, -0.004) in longitudinal analyses. A greater effect was observed for weekday sleep duration than weekend sleep duration but variability in duration was not related to BMI z-score. While sleep timing (onset or midpoint of sleep) was not related to BMI, children who were awake in the night more frequently (0.19; 0.06, 0.32) or for longer periods (0.18; 0.06, 0.36) had significantly higher BMI z-scores cross-sectionally, but only the estimates for total time awake (minutes) were significant longitudinally (increase in BMI z-score of 0.04 for each additional hour awake). CONCLUSION: The beneficial effect of a longer sleep duration on BMI was consistent in children, whereas evidence for markers of sleep quality and timing were more variable.

Spot urine and 24-h diet recall estimates of dietary sodium intake from the 2008/09 New Zealand Adult Nutrition Survey: a comparison.

BACKGROUND: We aimed to test the difference between estimates of dietary sodium intake using 24-h diet recall and spot urine collection in a large sample of New Zealand adults. METHODS: We analysed spot urine results, 24-h diet recall, dietary habits questionnaire and anthropometry from a representative sample of 3312 adults aged 15 years and older who participated in the 2008/09 New Zealand Adult Nutrition Survey. Estimates of adult population sodium intake were derived from 24-h diet recall and spot urine sodium using a formula derived from analysis of INTERSALT data. Correlations, limits of agreement and mean difference were calculated for the total sample, and for population subgroups. RESULTS: Estimated total population 24-h urinary sodium excretion (mean (95% CI)) from spot urine samples was 3035 mg (2990, 3079); 3612 mg (3549, 3674) for men and 2507 mg (2466, 2548) for women. Estimated mean usual daily sodium intake from 24-h diet recall data (excluding salt added at the table) was 2564 mg (2519, 2608); 2849 mg (2779, 2920) for men and 2304 mg (2258, 2350) for women. Correlations between estimates were poor, especially for men, and limits of agreement using Bland-Altman mean difference analysis were wide. CONCLUSIONS: There is a poor agreement between estimates of individual sodium intake from spot urine collection and those from 24-hour diet recall. Although, both 24-hour dietary recall and estimated urinary excretion based on spot urine indicate mean population sodium intake is greater than 2 g, significant differences in mean intake by method deserve further investigation in relation to the gold standard, 24-hour urinary sodium excretion.

Change of School Playground Environment on Bullying: A Randomized Controlled Trial.

OBJECTIVE: To investigate whether increasing risk and challenge in primary school playgrounds influences interactions between children. METHODS: In a 2-year cluster-randomized controlled trial, 8 control schools were asked to not change their play environment, whereas 8 intervention schools increased opportunities for risk and challenge (eg, rough-and-tumble play), reduced rules, and added loose parts (eg, tires). Children (n = 840), parents (n = 635), and teachers (n = 90) completed bullying questionnaires at baseline, 1 (postintervention), and 2 (follow-up) years. RESULTS: Intervention children reported higher odds of being happy at school (at 2 years, odds ratio [OR]: 1.64; 95% confidence interval [CI]: 1.20-2.25) and playing with more children (at 1 year, OR: 1.66; 95% CI: 1.29-2.15) than control children. Although intervention children indicated they were pushed/shoved more (OR: 1.33; 95% CI: 1.03-1.71), they were less likely to tell a teacher (OR: 0.69; 95% CI: 0.52-0.92) at 2 years. No significant group differences were observed in parents reporting whether children had "ever" been bullied at school (1 year: P = .23; 2 years: P = .07). Intervention school teachers noticed more bullying in break time at 1 year (difference in scores: 0.20; 95% CI: 0.06-0.34; P = .009), with no corresponding increase in children reporting bullying to teachers (both time points, P ≥ .26). CONCLUSIONS: Few negative outcomes were reported by children or parents, except for greater pushing/shoving in intervention schools. Whether this indicates increased resilience as indicated by lower reporting of bullying to teachers may be an unanticipated benefit.

Advice to walk after meals is more effective for lowering postprandial glycaemia in type 2 diabetes mellitus than advice that does not specify timing: a randomised crossover study.

AIMS/HYPOTHESIS: Regular physical activity is a cornerstone of diabetes management. We conducted a study to evaluate whether specifying the timing of walking in relation to meals enhances the benefits conferred by current physical activity guidelines. METHODS: A total of 41 adults with type 2 diabetes mellitus (mean ± SD age 60 ± 9.9 years; mean diabetes duration 10 years) participated in this randomised, crossover study. Randomisation was by a computer-generated protocol. For periods of 2 weeks, advice to walk 30 min each day was compared with advice to walk for 10 min after each main meal. Both sets of advice met current physical activity guidelines for people with type 2 diabetes mellitus. Physical activity was measured by accelerometry over the full intervention, and glycaemia was measured using continuous glucose monitoring in 5 min intervals over 7 days. The primary outcome of postprandial glycaemia was assessed during the 3 h after a meal by the incremental area under the blood glucose curve (iAUC). RESULTS: The iAUC was significantly lower when participants walked after meals compared with on a single daily occasion (ratio of geometric means 0.88, 95% CI 0.78, 0.99). The improvement was particularly striking after the evening meal (0.78, 95% CI 0.67, 0.91) when the most carbohydrate was consumed and sedentary behaviours were highest. One participant died during the 30 day washout period between interventions, but participation in this study was not judged to contribute to this unfortunate event. CONCLUSIONS/INTERPRETATION: The benefits relating to physical activity following meals suggest that current guidelines should be amended to specify post-meal activity, particularly when meals contain a substantial amount of carbohydrate. TRIAL REGISTRATION: ACTRN12613000832774 FUNDING: : This study was supported by grants from the University of Otago and the New Zealand Artificial Limb Service. Glycated albumin reagents were provided by Asahi Kasei.

Serum and erythrocyte folate status of New Zealand women of childbearing age following a countrywide voluntary programme by the baking industry to fortify bread with folic acid.

OBJECTIVE: To estimate the folate status of New Zealand women of childbearing age following the introduction, in 2010, of a new voluntary folic acid fortification of bread programme. DESIGN: The 2011 Folate and Women's Health Survey was a cross-sectional survey of women aged 18-44 years carried out in 2011. The survey used a stratified random sampling technique with the Electoral Roll as the sampling frame. Women were asked about consumption of folic-acid-fortified breads and breakfast cereals in a telephone interview. During a clinic visit, blood was collected for serum and erythrocyte folate measurement by microbiological assay. SETTING: A North Island (Wellington) and South Island (Dunedin) city centre in New Zealand. SUBJECTS: Two hundred and eighty-eight women, of whom 278 completed a clinic visit. RESULTS: Geometric mean serum and erythrocyte folate concentrations were 30 nmol/l and 996 nmol/l, respectively. Folate status was 30-40 % higher compared with women of childbearing age sampled as part of a national survey in 2008/09, prior to the introduction of the voluntary folic acid bread fortification programme. In the 2011 Folate and Women's Health Survey, reported consumption of fortified bread and fortified breakfast cereal in the past week was associated with 25 % (P=0·01) and 15 % (P=0·04) higher serum folate concentrations, respectively. CONCLUSIONS: Serum and erythrocyte folate concentrations have increased in New Zealand women of childbearing age since the number of folic-acid-fortified breads was increased voluntarily in 2010. Consumption of fortified breads and breakfast cereals was associated with a higher folate status.

Trends in serum total cholesterol and dietary fat intakes in New Zealand between 1989 and 2009.

OBJECTIVE: To describe trends in serum cholesterol and dietary fat intakes for New Zealand adults between 1989 and 2008/09. METHODS: Serum total cholesterol concentrations and dietary fat intakes were analysed for 9,346 New Zealanders aged 15-98 years (52% women) who participated in three national surveys in 1989, 1997 and 2008/09. RESULTS: Population mean serum cholesterol decreased from 6.15 mmol/L in 1989 to 5.39 mmol/L in 2008/09. Mean saturated fat intake decreased from 15.9% of energy intake in 1989 to 13.1% in 2008/09. Between 1997 and 2008/09, unsaturated fat intake increased and fat from butter and milk decreased. Older adults had the largest decrease in serum cholesterol (1.35 mmol/L). CONCLUSIONS: The decrease in serum cholesterol is substantially larger than reported for many other high-income countries, and occurred in parallel with changes in dietary fat intakes and, for older adults, increased use of cholesterol-lowering medications. IMPLICATION: Given the demonstrated role of reduced saturated fat intake on lowering serum cholesterol, and as population average serum cholesterol levels and saturated fat intakes exceed recommended levels, initiatives to further encourage reductions in saturated fat are imperative.

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.

Blood pressure and hypertension in New Zealand: results from the 2008/09 Adult Nutrition Survey.

AIMS: To report the blood pressure results from the 2008/09 New Zealand Adult Nutrition Survey (2008/09NZANS). METHODS: Blood pressure measurements were available for 4,407 adults who were part of a survey involving face-to-face interviews with 4,721 New Zealanders aged 15 years and over. Three measurements were taken one minute apart, and the mean of the second and third readings has been used for this analysis. Hypertension was defined as systolic blood pressure (SBP) greater than and equal to 140 mmHg or diastolic blood pressure (DBP) greater than and equal to 90 mmHg or self reported use of antihypertensive medications. Comparisons were made with previously published New Zealand population blood pressure estimates. RESULTS: Mean SBP for the New Zealand adult population was 126 mmHg. The prevalence of hypertension was 31%, with 15% reporting taking antihypertensive medication. Mean SBP has increased since 2002/03 for New Zealand European and others (NZEO) aged 35-54 years and Maori aged 35-74 years, reversing a downward trend observed in NZEO between 1982 and 2002. CONCLUSIONS: The increasing blood pressure levels are concerning. Given the importance of elevated blood pressure as a risk factor for cardiovascular disease, intensive screening, public health measures aimed at lowering population blood pressure, and further population monitoring are warranted.

Prevalence of diagnosed and undiagnosed diabetes and prediabetes in New Zealand: findings from the 2008/09 Adult Nutrition Survey.

AIM: To describe the prevalence of diagnosed and undiagnosed diabetes and prediabetes for New Zealand adults. METHODS: The 2008/09 New Zealand Adult Nutrition Survey was a nationally representative, cross-sectional survey of 4,721 New Zealanders aged 15 years and above. Self-reported diabetes and the 2010 American Diabetes Association cutoffs for HbA1c were used to define diagnosed diabetes, undiagnosed diabetes and prediabetes. Prevalence rates were calculated and age-specific diagnosed diabetes rates were compared with those from the Virtual Diabetes Register. RESULTS: Overall, prevalence of diabetes was 7.0%, and prevalence of prediabetes 18.6%. Prevalence of diabetes was higher in men (8.3%, 95% CI: 6.4, 10.1) than in women (5.8%, 95% CI: 4.7, 7.0), and was higher among the obese (14.2%, 95% CI: 11.6, 16.9) compared with the normal weight group (2.4%, 95% CI: 1.4, 3.6). Prevalence of undiagnosed diabetes was highest among Pacific people (6.4%, 95% CI: 3.8, 9.1) compared with Maori (2.2%, 95% CI: 1.2, 3.1) and New Zealand European and Others (1.5%, 95% CI: 0.9, 2.1). CONCLUSION: The high prevalence of prediabetes indicates the prevalence of diabetes will continue to increase in New Zealand. Implementation of effective evidence-based prevention strategies is required to reduce the increasing costs of the diabetes epidemic.

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.

Clinical validation of the quick dynamic insulin sensitivity test.

The quick dynamic insulin sensitivity test (DISTq) can yield an insulin sensitivity result immediately after a 30-min clinical protocol. The test uses intravenous boluses of 10 g glucose and 1 U insulin at t = 1 and 11 min, respectively, and measures glucose levels in samples taken at t = 0, 10, 20, and 30 min. The low clinical cost of the protocol is enabled via robust model formulation and a series of population-derived relationships that estimate insulin pharmacokinetics as a function of insulin sensitivity (SI). Fifty individuals underwent the gold standard euglycaemic clamp (EIC) and DISTq within an eight-day period. SI values from the EIC and two DISTq variants (four-sample DISTq and two-sample DISTq30) were compared with correlation, Bland-Altman and receiver operator curve analyses. DISTq and DISTq30 correlated well with the EIC [R = 0.76 and 0.75, and receiver operator curve c-index = 0.84 and 0.85, respectively]. The median differences between EIC and DISTq/DISTq30 SI values were 13% and 22%, respectively. The DISTq estimation method predicted individual insulin responses without specific insulin assays with relative accuracy and thus high equivalence to EIC SI values was achieved. DISTq produced very inexpensive, relatively accurate immediate results, and can thus enable a number of applications that are impossible with established SI tests.

Understanding the new HbA1c units for the diagnosis of Type 2 diabetes.

In New Zealand laboratories the measurement of glycated haemoglobin (HbA1c) for diagnosis of diabetes is now only reported in SI units of mmol/mol. HbA1c is now recommended as the preferred test to diagnose diabetes in most circumstances. The requirement for a second positive test in asymptomatic individuals is retained. An HbA1c greater than and equal to 50 mmol/mol (repeated on a second occasion in asymptomatic patients) is diagnostic of diabetes and a value less than and equal to 40 mmol/mol represents normal glucose tolerance. For patients with an initial HbA1c result of 41-49 mmol/mol, cardiovascular risk assessment and lifestyle interventions are recommended with repeat HbA1c screening in 6-12 months. For patients whose HbA1c is less than and equal to 40 mmol/mol, repeat screening (including for CVD risk) at intermittent intervals is recommended as per published guidelines.

Differences in erythrocyte folate concentrations in older adults reached steady-state within one year in a two-year, controlled, 1 mg/d folate supplementation trial.

Daily supplementation with folate increases erythrocyte folate concentrations; however, the time to reach steady-state concentrations has not been empirically demonstrated. Previous predictions of time to steady state or time to 90% steady-state concentration, based on modeling changes in erythrocyte folate during short-term trials, range widely from 40 to 86 wk. We sought to determine the time to steady-state erythrocyte folate concentrations following the initiation of daily folate supplementation using data collected from a 2-y, double-blind, placebo-controlled, randomized trial involving 276 participants aged 65 y or older. The daily supplement contained 1 mg of folate. Erythrocyte folate concentrations were measured, using a microbiological assay, at baseline and at 6, 12, 18, and 24 mo. The mean plasma and erythrocyte folate concentrations in the folate-supplemented group were higher than in the placebo group at 6, 12, 18, and 24 mo (P < 0.001). Adjusted for baseline differences, the difference in erythrocyte folate concentrations between the folate and placebo group at 6 mo was 1.78 µmol/L (95% CI: 1.62-1.95 µmol/L). The difference increased significantly to 2.02 µmol/L (95% CI: 1.85-2.18 µmol/L) at 12 mo. This difference (between the folate and placebo groups) did not significantly change after a further year of folate supplementation; at 18 mo, it was 2.09 µmol/L (95% CI: 1.92-2.27 µmol/L) and at 24 mo it was 1.98 µmol/L (95% CI: 1.18-2.15 µmol/L). Twelve months of daily folate supplementation with 1 mg is sufficient time to cause erythrocyte folate concentrations to reach a new steady state.

Dietary sodium loading in normotensive healthy volunteers does not increase arterial vascular reactivity or blood pressure.

BACKGROUND: Studies of dietary sodium on vascular function and blood pressure in normotensive volunteers have shown conflicting results. There are very limited data available on the effect of chronic sodium loading from a low-sodium diet to a high-sodium diet on vascular function and blood pressure in normotensive volunteers. OBJECTIVE: To assess the effect of modifying dietary sodium intake on arterial function and surrogate markers of arterial remodelling in normal healthy volunteers. DESIGN: Twenty-three normotensive volunteers met the inclusion criteria. After a 2 week run-in with a low-sodium diet (60 mmol/day), the participants maintained their low-sodium diets and were randomly assigned to receive sequentially one of three interventions for 4 weeks, with a 2 week washout between interventions: sodium-free tomato juice (A), tomato juice containing 90 mmol Na (B) and tomato juice containing 140 mmol Na (C). The outcomes measured were changes in pulse wave velocity (PWV), systolic blood pressure and diastolic blood pressure. RESULTS: There was no difference in PWV between interventions (B-A 0.00 m/s, 95% CI: -0.30, 0.31 m/s; C-A 0.01 m/s, 95% CI: -0.38, 0.40 m/s). There was also no change in pulse wave analysis, systolic or diastolic blood pressure between interventions. There was an appropriate increase in urinary sodium excretion in the added sodium interventions. CONCLUSION: Dietary salt loading did not produce significant increases in PWV and blood pressure in normotensive subjects with systolic blood pressure <130 mmHg. The lack of an observed effect supports Guyton's pressure-natriuresis hypothesis with appropriate renal excretion of the excess sodium load.