Benefits of caloric restriction for cardiometabolic health, including type 2 diabetes mellitus risk

In the United States, life expectancy has markedly increased during the past century, and population ageing is expected to double within the next 25 years. The process of ageing in a population is associated with the development of chronic diseases, such as type 2 diabetes mellitus, that can be prevented, and even reversed, with the implementation of healthy lifestyle interventions. The evidence to date, consolidated by the numerous epidemiological studies and clinical trials conducted, suggests that caloric restriction is an effective nutritional intervention for preventing most of these age-related conditions. At a metabolic level, caloric restriction with adequate nutrition has been shown to improve insulin sensitivity, reduce fasting glucose and insulin concentration and prevent obesity, type 2 diabetes, hypertension and chronic inflammation. The purpose of this article is to review current knowledge of the metabolic and clinical implications of caloric restriction with adequate nutrition for the prevention of type 2 diabetes and cardiovascular disease.

Early response to preventive strategies in the Diabetes Prevention Program

BACKGROUND

Recommendations for diabetes prevention in patients with prediabetes include lifestyle modification and metformin. However, the significance of early weight loss and glucose measurements when monitoring response to these proven interventions is unknown.

OBJECTIVE

To quantify the relationship between early measures of weight and glucose and subsequent diabetes in patients undergoing diabetes prevention interventions.

DESIGN

Analysis of results from a randomized controlled trial in 27 academic medical centers in the United States.

PARTICIPANTS/INTERVENTIONS

3,041 adults with hyperglycemia randomized to lifestyle (n = 1,018), metformin (n = 1,036), or placebo (n = 987) with complete follow-up in The Diabetes Prevention Program.

MAIN MEASURES

Independent variables were weight loss at 6 and 12 months; fasting glucose (FG) at 6 months; hemoglobin A1c (HbA1c) at 6 months; and post-load glucose at 12 months. The main outcome was time to diabetes diagnosis.

KEY RESULTS

After 6 months, 604 participants developed diabetes in the lifestyle (n = 140), metformin (n = 206), and placebo (n = 258) arms over 2.7 years. In the lifestyle arm, 6-month weight loss predicted decreased diabetes risk in a graded fashion: adjusted HR (95 % CI) 0.65 (0.35-1.22), 0.62 (0.33-1.18), 0.46 (0.24-0.87), 0.34 (0.18-0.64), and 0.15 (0.07-0.30) for 0-<3 %, 3-<5 %, 5-<7 %, 7-<10 %, and ≥10 % weight loss, respectively (reference: weight gain). Attainment of optimal 6-month FG and HbA1c and 12-month post-load glucose predicted >60 % lower diabetes risk across arms. We found a significant interaction between 6-month weight loss and FG in the lifestyle arm (P = 0.038).

CONCLUSION

Weight and glucose at 6 and 12 months strongly predict lower subsequent diabetes risk with a lifestyle intervention; lower FG predicts lower risk even with substantial weight loss. Early reduction in glycemia is a stronger predictor of future diabetes risk than weight loss for metformin. We offer the first evidence to guide clinicians in making interval management decisions for high-risk patients undertaking measures to prevent diabetes.

Increased leg blood flow and improved femoral artery shear patterns in metabolic syndrome after a diet and exercise programme

BACKGROUND

Altered vascular shear profiles may contribute to the development of atherosclerosis. Physical activity promotes anti-atherogenic shear patterns, resulting in reduced cardiovascular disease risk. Adults with metabolic syndrome (MetSyn) are at increased risk of developing atherosclerosis and cardiovascular disease. Thus, we hypothesized that conduit artery antegrade shear rate (ASR) would increase and retrograde shear rate (RSR) and oscillatory shear indices (OSI) would decrease in MetSyn patients (n = 16, 51 ± 2 years) after participation in a diet and exercise programme (DEP).

METHODS

Blood flow (Doppler ultrasound, brachial and femoral arteries) was measured, and shear rates were calculated in MetSyn patients before and after 12 weeks of DEP participation. In addition, plasma samples were collected to measure atherogenic markers.

RESULTS

Diet and exercise programme participation increased resting leg blood flow and femoral artery ASR (P ≤ 0·05), and tended to decrease OSI (P = 0·09); RSR did not change (P>0·05). No changes in resting arm blood flow or ASR were observed (P>0·05), and both RSR and OSI increased after participation (P≤0·05). DEP participation reduced plasma vascular cell adhesion molecule(VCAM)-1 (P = 0·03), with a trend for reduced intercellular cell adhesion molecule(ICAM)-1 (P = 0·09) (i.e. atherogenic markers).

CONCLUSION

Modest changes in diet and physical activity result in limb-specific improvements in vascular shear profiles and reduced systemic markers of atherosclerotic risk in MetSyn patients. These data provide novel physiologic insight into adaptations that may limit the progression of atherosclerosis in patients with MetSyn.

Low glycaemic index diets improve glucose tolerance and body weight in women with previous history of gestational diabetes: a six months randomized trial

BACKGROUND

Gestational Diabetes Mellitus (GDM) increases risks for type 2 diabetes and weight management is recommended to reduce the risk. Conventional dietary recommendations (energy-restricted, low fat) have limited success in women with previous GDM. The effect of lowering Glycaemic Index (GI) in managing glycaemic variables and body weight in women post-GDM is unknown.

OBJECTIVE

To evaluate the effects of conventional dietary recommendations administered with and without additional low-GI education, in the management of glucose tolerance and body weight in Asian women with previous GDM.

METHOD

Seventy seven Asian, non-diabetic women with previous GDM, between 20- 40y were randomised into Conventional healthy dietary recommendation (CHDR) and low GI (LGI) groups. CHDR received conventional dietary recommendations only (energy restricted, low in fat and refined sugars, high-fibre). LGI group received advice on lowering GI in addition. Fasting and 2-h post-load blood glucose after 75 g oral glucose tolerance test (2HPP) were measured at baseline and 6 months after intervention. Anthropometry and dietary intake were assessed at baseline, three and six months after intervention. The study is registered at the Malaysian National Medical Research Register (NMRR) with Research ID: 5183.

RESULTS

After 6 months, significant reductions in body weight, BMI and waist-to-hip ratio were observed only in LGI group (P<0.05). Mean BMI changes were significantly different between groups (LGI vs. CHDR: -0.6 vs. 0 kg/m2, P= 0.03). More subjects achieved weight loss ≥5% in LGI compared to CHDR group (33% vs. 8%, P=0.01). Changes in 2HPP were significantly different between groups (LGI vs. CHDR: median (IQR): -0.2(2.8) vs. +0.8 (2.0) mmol/L, P=0.025). Subjects with baseline fasting insulin≥2 μIU/ml had greater 2HPP reductions in LGI group compared to those in the CHDR group (-1.9±0.42 vs. +1.31±1.4 mmol/L, P<0.001). After 6 months, LGI group diets showed significantly lower GI (57±5 vs. 64±6, P<0.001), GL (122±33 vs. 142±35, P=0.04) and higher fibre content (17±4 vs.13±4 g, P<0.001). Caloric intakes were comparable between groups.

CONCLUSION

In women post-GDM, lowering GI of healthy diets resulted in significant improvements in glucose tolerance and body weight reduction as compared to conventional low-fat diets with similar energy prescription.

Culturally adapting the prevention of diabetes and obesity in South Asians (PODOSA) trial

Type 2 diabetes is extremely common in South Asians, e.g. in men from Pakistani and Indian populations it is about three times as likely as in the general population in England, despite similarities in body mass index. Lifestyle interventions reduce the incidence of diabetes. Trials in Europe and North America have not, however, reported on the impact on South Asian populations separately or provided the details of their cross-cultural adaptation processes. Prevention of diabetes and obesity in South Asians (PODOSA) is a randomized, controlled trial in Scotland of an adapted, lifestyle intervention aimed at reducing weight and increasing physical activity to reduce type 2 diabetes in Indians and Pakistanis. The trial was adapted from the Finnish Diabetes Prevention Study. We describe, reflect on and discuss the following key issues: The core adaptations to the trial design, particularly the delivery of the intervention in homes by dietitians rather than in clinics. The use of both a multilingual panel and professional translators to help translate and/or develop materials. The processes and challenges of phonetic translation. How intervention resources were adapted, modified, newly developed and translated into Urdu and Gurmukhi (written Punjabi). The insights gained in PODOSA (including time pressures on investigators, imperfections in the adaptation process, the power of verbal rather than written information, the utilization of English and the mother-tongue languages simultaneously by participants and the costs) might help the research community, given the challenge of health promotion in multi-ethnic, urban societies.

Shared governance in building community capacity: A case study of sleep apnea

East Harlem has the highest diabetes mortality rate in New York City, NY. Using Community Based Participatory Research principles, the East Harlem Partnership for Diabetes Prevention-a community- academic partnership-formed to build community capacity with a goal to address health disparities in East Harlem. As part of prevention efforts, community partners chose to study the prevalence of obstructive sleep apnea and its relationship to pre-diabetes and progression to diabetes. However, community partners insisted any study of sleep apnea go beyond simple assessment to ensure the largely uninsured, minority population enrolled also have access to state of the art diagnosis and treatment. Through compromise and collaboration, the partnership developed a culturally appropriate and scientifically rigorous method to diagnose and treat sleep apnea as part of a novel research program.

Long-term effects of the Diabetes Prevention Program interventions on cardiovascular risk factors: a report from the DPP Outcomes Study

AIMS

Whether long-term cardiovascular risk is reduced by the Diabetes Prevention Program interventions is unknown. The aim of this study was to determine the long-term differences in cardiovascular disease risk factors and the use of lipid and blood pressure medications by the original Diabetes Prevention Program intervention group.

METHODS

This long-term follow-up (median 10 years, interquartile range 9.0-10.5) of the three-arm Diabetes Prevention Program randomized controlled clinical trial (metformin, intensive lifestyle and placebo), performed on 2766 (88%) of the Diabetes Prevention Program participants (who originally had impaired glucose tolerance), comprised a mean of 3.2 years of randomized treatment, approximately 1-year transition (during which all participants were offered intensive lifestyle intervention) and 5 years follow-up (Diabetes Prevention Program Outcomes Study). During the study, participants were followed in their original groups with their clinical care being provided by practitioners outside the research setting. The study determined lipoprotein profiles and blood pressure and medication use annually.

RESULTS

After 10 years' follow-up from Diabetes Prevention Program baseline, major reductions were seen for systolic (-2 to -3) and diastolic (-6 to -6.5 mmHg) blood pressure, and for LDL cholesterol (-0.51 to -0.6 mmol/l) and triglycerides (-0.23 to -0.25 mmol/l) in all groups, with no between-group differences. HDL cholesterol also rose significantly (0.14 to 0.15 mmol/l) in all groups. Lipid (P = 0.01) and blood pressure (P = 0.09) medication use, however, were lower for the lifestyle group during the Diabetes Prevention Program Outcomes Study.

CONCLUSION

Overall, intensive lifestyle intervention achieved, with less medication, a comparable long-term effect on cardiovascular disease risk factors, to that seen in the metformin and placebo groups.

Interactive learning activities for the middle school classroom to promote healthy energy balance and decrease diabetes risk in the HEALTHY primary prevention trial

The HEALTHY trial evaluated the effectiveness of a multicomponent intervention program to reduce risk for type 2 diabetes in middle school students. The comprehensive intervention addressed nutrition, physical activity, and behavior in the context of a social marketing-based communications campaign to promote healthy energy balance. One element was a classroom-based program called FLASH (Fun Learning Activities for Student Health). Five FLASH modules were delivered, one per semester. Process evaluation data were collected from teachers at 21 schools and study staff at seven national sites via survey, interview, and in-class observation. Data from the first four modules were evaluated and showed that FLASH was delivered with high fidelity. Sessions that required peer interaction were rated as the most effective in engaging students and promoting knowledge. Study-provided material resources and on-site support were identified as key facilitators. Student misbehavior was viewed as the greatest barrier. Although the high level of support provided by the study is not likely to be replicated in school systems, those developing wellness policies, health curricula, and teacher training programs may benefit from using the evidence-supported, publicly available HEALTHY materials in their efforts to reduce diabetes risk factors in middle school youth.

Sustaining modified behaviours learnt in a diabetes prevention program in regional Australia: the role of social context

BACKGROUND

The Greater Green Triangle diabetes prevention program was conducted in primary health care setting of Victoria and South Australia in 2004-2006. This program demonstrated significant reductions in diabetes risk factors which were largely sustained at 18 month follow-up. The theoretical model utilised in this program achieved its outcomes through improvements in coping self-efficacy and planning. Previous evaluations have concentrated on the behavioural components of the intervention. Other variables external to the main research design may have contributed to the success factors but have yet to be identified. The objective of this evaluation was to identify the extent to which participants in a diabetes prevention program sustained lifestyle changes several years after completing the program and to identify contextual factors that contributed to sustaining changes.

METHODS

A qualitative evaluation was conducted. Five focus groups were held with people who had completed a diabetes prevention program, several years later to assess the degree to which they had sustained program strategies and to identify contributing factors.

RESULTS

Participants value the recruitment strategy. Involvement in their own risk assessment was a strong motivator. Learning new skills gave participants a sense of empowerment. Receiving regular pathology reports was a means of self-assessment and a motivator to continue. Strong family and community support contributed to personal motivation and sustained practice.

CONCLUSIONS

Family and local community supports constitute the contextual variables reported to contribute to sustained motivation after the program was completed. Behaviour modification programs can incorporate strategies to ensure these factors are recognised and if necessary, strengthened at the local level.

Opportunistic screening and health promotion for type 2 diabetes: an expanding public health role for the community pharmacist

BACKGROUND

Early detection to identify people at risk of diabetes is an important approach to prevent or delay type 2 diabetes. This study aimed to implement the Diabetes Prevention Program in community pharmacy using a diabetes risk prediction tool.

METHODS

The program was conducted in seven pharmacies in Bangkok, Thailand. Participants were the pharmacy's clients aged ≥ 35 years without the history of diabetes. A validated risk prediction tool was used to assess individuals' diabetes risk. Educational information was offered to all participants. Those with a high risk score (≥ 9 out of 17) were offered a self-check of fasting capillary blood glucose (CBG). A referral was made for those with CBG ≥ 126 mg/dl.

RESULTS

During a 3-month service, 397 individuals participated in the program. Nearly half of the participants (49.4%) were at a high risk of diabetes (risk score: ≥ 9). Ninety five (48.5%) of these high risk individuals undertook fasting CBG. Elevated fasting CBG (≥ 126 mg/dl) was found in 12 persons (12.7%). Overall, two patients with diabetes were identified during the provision of the program.

CONCLUSIONS

The Diabetes Prevention Program in community pharmacies uncovered half of the clients who were at risk of diabetes and provided an opportunity for participants to learn more about the prevention of diabetes.

Performance of a multi-marker diabetes risk score in the Insulin Resistance Atherosclerosis Study (IRAS), a multi-ethnic US cohort

BACKGROUND

This study compares a previously developed Diabetes Risk Score to commonly used clinical tools for type 2 diabetes risk evaluation in the Insulin Resistance Atherosclerosis Study (IRAS) cohort, a multi-ethnic US cohort. Available as a clinical test, the PreDx® Diabetes Risk Score uses fasting concentrations of adiponectin, C-reactive protein, ferritin, interleukin-2 receptor alpha, HbA(1c) , glucose and insulin, plus age and gender to predict 5-year risk of diabetes. It was developed in a Northern European population.

METHODS

The Diabetes Risk Score was measured using archived fasting plasma specimens from 722 non-diabetic IRAS participants, 17.6% of whom developed diabetes during 5.2 years median follow-up (inter-quartile range: 5.1-5.4 years). The study included non-Hispanic whites (41.8%), Hispanics (34.5%) and African Americans (23.7%). Performance of the algorithm was evaluated by area under the receiver operating characteristic curve (AROC) and risk reclassification against other tools.

RESULTS

The Diabetes Risk Score discriminates participants who developed diabetes from those who did not significantly better than fasting glucose (AROC = 0.763 versus 0.710, p = 0.003). The Diabetes Risk Score performed equally well in subpopulations defined by race/ethnicity or gender. The Diabetes Risk Score provided a significant net reclassification improvement of 0.24 (p = 0.01) when comparing predefined low/moderate/high Diabetes Risk Score categories to metabolic syndrome risk factor counting. The Diabetes Risk Score complemented the use of the oral glucose tolerance test by identifying high risk patients with impaired fasting glucose but normal glucose tolerance, 33% of whom converted.

CONCLUSIONS

Measuring the Diabetes Risk Score of elevated-risk US patients could help physicians decide which patients warrant more intensive intervention. The Diabetes Risk Score performed equally well across the ethnic subpopulations present in this cohort.

An innovative approach to providing lifestyle education and behaviour change to prevent type 2 diabetes

Introduction

Diabetes is one of the major health challenges of our time. Diabetes UK recently estimated 10% of the total NHS budget is spent on diabetes care. NICE guidance “Prevention of type 2 diabetes in adults” (2011) and “Prevention of type 2 diabetes in high-risk groups” (currently consultation phase) emphasises the importance of prevention. Impaired glucose tolerance (IGT) is a precursor for the development of type 2 diabetes and is additionally associated with increased cardiovascular risk. Positive lifestyle changes (healthy eating, increased activity, weight reduction) have been proven to prevent or delay onset of type 2 diabetes in people diagnosed with IGT.

Aims and objectives

Working together, Greater Manchester CLAHRC and Salford’s NHS Diabetes Care Call team developed a six-month, telephone-based, lifestyle intervention programme for people with IGT. The aim was to provide a convenient, accessible and tailored service that would motivate and enable people to make positive behaviour changes to prevent or delay onset of type 2 diabetes. The programme was delivered by a team of trained health advisors who provided standardised, evidence-based education via a series of electronic scripts developed and maintained by the specialist diabetes team. Supporting resources, including a patient education leaflet and DVD designed in-house, were sent by post. Health advisors worked on an individual basis with participants and had access to an online directory of local services and groups to signpost appropriately. The project ran from May 2010 to January 2011, enrolling 55 people with IGT from seven GP practices in Salford. All calls were recorded on the electronic patient record, viewable across primary and secondary care.

Key results

All 55 participants completed the pathway.

Clinical Outcomes:

52% (n=26) reverted to normal fasting and glucose tolerance.

10% (n=5) reduced risk to impaired fasting glucose.

75% (n=38) confirmed weight loss, average 4.8 kg (5.3%) per person.

61% (n=31) reduced FINDRISC score by average 2.1 points per person.

88% (n=48) achieved or partially achieved their overall lifestyle goal.

Qualitative outcomes (from questionnaires and focus groups):

88% (n=36) participants reported increased understanding of blood results.

78% (n=32) participants reported definite increased confidence about how to reduce their own risk of developing type 2 diabetes.

90% (n=37) felt they received relevant, up to date advice about reducing diabetes risk.

GP practices reported high-levels of confidence that the service provided evidence-based dietary and lifestyle advice and motivational support.

Large-scale research studies strongly suggest lifestyle programmes preventing diabetes are cost effective. Cost benefit analysis of this project and extrapolation for whole population shows roll out is achievable with payback on investment in year three.

Conclusion

The IGT care call service is a highly scalable and cost-effective approach to preventing diabetes and amenable for ‘hard to reach’ groups. A full evaluation report was presented to NHS Salford Commissioning Board who have since allocated further funding, allowing further expansion of the project and longer-term follow-up of participants. This project recently won a Quality in Care (QiC) Diabetes award for “Best type 2 diabetes prevention initiative” (November 2011).

Frequency of diabetes, impaired fasting glucose, and glucose intolerance in high-risk groups identified by a FINDRISC survey in Puebla City, Mexico

BACKGROUND

As a first step in the prevention of diabetes, the International Diabetes Federation recommends identification of persons at risk using the Finnish type 2 Diabetes Risk Assessment (FINDRISC) survey. The frequency of diabetes mellitus, impaired fasting glucose, and glucose intolerance in high-risk groups identified by FINDRISC is unknown in our country. The aim of this study was to determine the frequency of diabetes mellitus, impaired fasting glucose, and glucose intolerance in higher-risk groups using a FINDRISC survey in an urban population.

METHODS

We used a television program to invite interested adults to fill out a survey at a television station. An oral glucose tolerance test was performed in all persons with a FINDRISC score ≥ 15 points (high-risk and very high-risk groups). Patients were classified as normal (fasting glucose < 100 mg/dL and 2-hour glucose < 140 mg/dL), or having impaired fasting glucose (fasting glucose 100-125 mg/dL and 2-hour glucose < 140 mg/dL), glucose intolerance (fasting glucose < 126 mg/dL and 2-hour glucose 140-199 mg/dL), and diabetes mellitus (fasting glucose ≥ 126 mg/dL or 2-hour glucose ≥ 200 mg/dL). We describe the frequency of each diagnostic category in this selected population according to gender and age.

RESULTS

A total of 186 patients had a score ≥ 15. The frequencies of diabetes mellitus, impaired fasting glucose, glucose intolerance, and normal glucose levels were 28.6%, 25.9%, 29.2%, and 16.2%, respectively. We found a higher frequency of diabetes mellitus and impaired fasting glucose in men than in women (33% versus 27% and 40% versus 21%, respectively) and more glucose intolerance in women than in men (34% versus 16%, P < 0.05). Patients with diabetes mellitus (52.55 ± 9.2 years) were older than those with impaired fasting glucose (46.19 ± 8.89 years), glucose intolerance (46.15 ± 10.9 years), and normal levels (41.9 ± 10.45 years, P < 0.05). We found a higher frequency of diabetes mellitus in those aged over 50 years than in younger subjects (46.15% versus 15.88%, respectively).

CONCLUSION

The FINDRISC survey is a very useful tool for identifying individuals at high risk of developing diabetes and prediabetic states, especially in those older than 50 years.

Prevention of type 2 diabetes: the strategic approach for implementation

A growing need exists to deliver effective and affordable prevention programs and to take urgent action to address the major public health challenge that diabetes represents. Achieving prevention of type 2 diabetes requires moving through a series of steps from basic science discovery to widespread distribution of effective interventions. Understanding the cellular level influences on diabetes prevention will help target particular interventions to those who may be most responsive. Several randomized controlled trials conducted throughout the world have demonstrated that type 2 diabetes can be prevented or delayed. Subsequent real-world translation studies have provided important information necessary to reduce cost and increase access. Ultimately achieving a population impact in diabetes prevention requires widespread distribution of effective interventions, which is supported by policies that help achieve sustainability and reach. The use of a global stakeholder network can help to share experiences and build on partner knowledge gained.

Effectively translating diabetes prevention: a successful model in a historically underserved community

Lifestyle interventions can prevent diabetes through weight loss, but they are rarely translated for use in underserved communities. The aim of this study was to describe how a community-academic partnership formed and developed a program to address local health disparities by developing a low-cost, culturally and economically appropriate, peer-led community-based diabetes prevention program. Using a participatory approach, the partnership chose to focus on diabetes prevention, and co-developed all intervention, recruitment, research, and evaluation strategies. The partnership's philosophy to maintain high clinical and scientific standards paired with their ability to represent and engage the community facilitated the development of a randomized controlled trial that achieved statistically significant and sustained weight loss, and the recruitment of a largely Spanish-speaking, low income, uninsured population. The success of this intervention lies in the partnership's commitment to the community, co-ownership of research, and a careful balance between academic rigor and community engagement and relevance.

Randomized controlled trial of two forms of self-management group education in Japanese people with impaired glucose tolerance

The aim of this study was to determine the effectiveness of education on diabetes prevention in subjects with impaired glucose tolerance. A total of 100 subjects of impaired glucose tolerance with hemoglobin A1c (HbA1c) levels ≥5.5 to <6.1% were assigned randomly to either support or control groups. All subjects received education in 8 sessions over a 6-month period. The support group consisted of 10 members collaborating with a dietitian or a nurse who learned coping skills by employing a participant-centered approach. Participants in the support group were required to keep a diary that monitored weight, food intake and blood glucose levels, while the control group attended several lectures. Subjects assigned to the support group had a reduction in mean HbA1c levels from 5.77 ± 0.36% at baseline to 5.39 ± 0.24% at the endpoint (p<0.01). Weight, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and triglyceride (TG) levels also decreased (p<0.01) in the support group, whereas subjects in the control group had no observable reduction in these indices. After intervention, participants of the support group had improvements in their 2-h post-meal blood glucose levels. Support group education can be effective for improving glycemic control in participants when carried out in collaboration with educators and other team members.

Ileal interposition surgery improves glucose and lipid metabolism and delays diabetes onset in the UCD-T2DM rat

BACKGROUND & AIMS

Bariatric surgery has been shown to reverse type 2 diabetes; however, mechanisms by which this occurs remain undefined. Ileal interposition (IT) is a surgical model that isolates the effects of increasing delivery of unabsorbed nutrients to the lower gastrointestinal tract. In this study we investigated effects of IT surgery on glucose tolerance and diabetes onset in UCD-T2DM (University of California at Davis type 2 diabetes mellitus) rats, a polygenic obese animal model of type 2 diabetes.

METHODS

IT or sham surgery was performed on 4-month-old male UCD-T2DM rats. All animals underwent oral glucose tolerance testing (OGTT). A subset was killed 2 months after surgery for tissue analyses. The remainder was followed until diabetes onset and underwent oral fat tolerance testing (OFTT).

RESULTS

IT surgery delayed diabetes onset by 120 +/- 49 days compared with sham surgery (P < .05) without a difference in body weight. During OGTT, IT-operated animals exhibited lower plasma glucose excursions (P < .05), improved early insulin secretion (P < .01), and 3-fold larger plasma glucagon-like peptide-1(7-36) (GLP-1(7-36)) excursions (P < .001), and no difference in glucose-dependent insulinotropic polypeptide responses compared with sham-operated animals. Total plasma peptide YY (PYY) excursions during OFTT were 3-fold larger in IT-operated animals (P < .01). IT-operated animals exhibited lower adiposity (P < .05), smaller adipocyte size (P < .05), 25% less ectopic lipid deposition, lower circulating lipids, and greater pancreatic insulin content compared with sham-operated animals (P < .05).

CONCLUSIONS

IT surgery delays the onset of diabetes in UCD-T2DM rats which may be related to increased nutrient-stimulated secretion of GLP-1(7-36) and PYY and improvements of insulin sensitivity, beta-cell function, and lipid metabolism.

The role of diet and lifestyle in primary, secondary, and tertiary diabetes prevention: a review of meta-analyses

Prevention of diabetes is crucial to lowering disease incidence, and thus minimizing the individual, familial, and public health burden. The purpose of this review is to gather current information from meta-analyses on dietary and lifestyle practices concerning reduction of risk to develop type 2 diabetes. Low glycemic index dietary patterns reduce both fasting blood glucose and glycated proteins independent of carbohydrate consumption. Diets rich in whole-grain, cereal high fiber products, and non-oil-seed pulses are beneficial. Whereas, frequent meat consumption has been shown to increase risk. Regarding non-alcoholic beverages, 4 cups/day of filtered coffee or tea are associated with a reduced diabetes risk. In contrast, the consumption of alcoholic beverages should not exceed 1-3 drinks/day. Intake of vitamin E, carotenoids, and magnesium can be increased to counteract diabetes risk. Obesity is the most important factor accounting for more than half of new diabetes' cases; even modest weight loss has a favorable effect in preventing the appearance of diabetes. Also, physical exercise with or without diet contributes to a healthier lifestyle, and is important for lowering risk. Finally, there is a positive association between smoking and risk to develop type 2 diabetes. As far as secondary and tertiary prevention is concerned, for persons already diagnosed with diabetes, there is limited evidence of the effectiveness of diet or lifestyle modification on glycemic control, but further studies are necessary.

Rationale, design and methods of the HEALTHY study nutrition intervention component

The HEALTHY study was a randomized, controlled, multicenter and middle school-based, multifaceted intervention designed to reduce risk factors for the development of type 2 diabetes. The study randomized 42 middle schools to intervention or control, and followed students from the sixth to the eighth grades. Here we describe the design of the HEALTHY nutrition intervention component that was developed to modify the total school food environment, defined to include the following: federal breakfast, lunch, after school snack and supper programs; a la carte venues, including snack bars and school stores; vending machines; fundraisers; and classroom parties and celebrations. Study staff implemented the intervention using core and toolbox strategies to achieve and maintain the following five intervention goals: (1) lower the average fat content of foods, (2) increase the availability and variety of fruits and vegetables, (3) limit the portion sizes and energy content of dessert and snack foods, (4) eliminate whole and 2% milk and all added sugar beverages, with the exception of low fat or nonfat flavored milk, and limit 100% fruit juice to breakfast in small portions and (5) increase the availability of higher fiber grain-based foods and legumes. Other nutrition intervention component elements were taste tests, cafeteria enhancements, cafeteria line messages and other messages about healthy eating, cafeteria learning laboratory (CLL) activities, twice-yearly training of food service staff, weekly meetings with food service managers, incentives for food service departments, and twice yearly local meetings and three national summits with district food service directors. Strengths of the intervention design were the integration of nutrition with the other HEALTHY intervention components (physical education, behavior change and communications), and the collaboration and rapport between the nutrition intervention study staff members and food service personnel at both school and district levels.

Ecodevelopmental contexts for preventing type 2 diabetes in Latino and other racial/ethnic minority populations

Diabetes is the sixth leading cause of death in the United States and it is now cited along with obesity as a global epidemic. Significant racial/ethnic disparities exist in the prevalence of diabetes within the US, with racial and ethnic minorities disproportionately affected by type 2 diabetes and its complications. Racial/ethnic and socioeconomic factors influence the development and course of diabetes at multiple levels, including genetic, individual, familial, community and national. From an ecodevelopmental perspective, cultural variables assessed at one level (e.g., family level dietary practices) may interact with other types of variables examined at other levels (e.g., the availability of healthy foods within a low-income neighborhood), thus prompting the need for a clear analysis of these systemic relationships as they may increase risks for disease. Therefore, the need exists for models that aid in "mapping out" these relationships. A more explicit conceptualization of such multi-level relationships would aid in the design of culturally relevant interventions that aim to maximize effectiveness when applied with Latinos and other racial/ethnic minority groups. This paper presents an expanded ecodevelopmental model intended to serve as a tool to aid in the design of multi-level diabetes prevention interventions for application with racial/ethnic minority populations. This discussion focuses primarily on risk factors and prevention intervention in Latino populations, although with implications for other racial/ethnic minority populations that are also at high risk for type 2 diabetes.

Sitagliptin: an oral agent for glucose control

Sitagliptin (Januvia™) is a new oral agent approved by the US FDA to treat Type 2 diabetes. This is the first approved agent in a new class of antihyperglycemics, dipeptidyl peptidase (DPP)-4 inhibitors. Sitagliptin selectively inhibits the action of DPP-4, the primary enzyme degrading the incretin hormones, allowing glucagon-like peptide-1 and glucose-dependent insulinotropic peptide to facilitate glucose regulation in response to a meal. Studies demonstrate that sitagliptin decreases hemaglobin A1c, postprandial glucose excursion and fasting plasma glucose. Sitagliptin presents some advantages over other drugs used in the management of diabetes. One advantage is its oral administration; another, is its low incidence of hypoglycemia, similar to that of a placebo. Sitagliptin has a low incidence of adverse events, consisting of stomach discomfort, diarrhea, upper respiratory infection, stuffy or runny nose, sore throat and headache. Unlike many other drugs used to treat diabetes, sitagliptin does not cause weight gain. Animal studies have shown that it can help prevent β-cell apoptosis and improve β-cell functioning; therefore, it may have a role in preventing diabetes, although human data are currently lacking.

Testing of diabetes-associated WFS1 polymorphisms in the Diabetes Prevention Program

AIMS/HYPOTHESIS

Wolfram syndrome (diabetes insipidus, diabetes mellitus, optic atrophy and deafness) is caused by mutations in the WFS1 gene. Recently, single nucleotide polymorphisms (SNPs) in WFS1 have been reproducibly associated with type 2 diabetes. We therefore examined the effects of these variants on diabetes incidence and response to interventions in the Diabetes Prevention Program (DPP), in which a lifestyle intervention or metformin treatment was compared with placebo.

METHODS

We genotyped the WFS1 SNPs rs10010131, rs752854 and rs734312 (H611R) in 3,548 DPP participants and performed Cox regression analysis using genotype, intervention and their interactions as predictors of diabetes incidence. We also evaluated the effect of these SNPs on insulin resistance and beta cell function at 1 year.

RESULTS

Although none of the three SNPs was associated with diabetes incidence in the overall cohort, white homozygotes for the previously reported protective alleles appeared less likely to develop diabetes in the lifestyle arm. Examination of the publicly available Diabetes Genetics Initiative genome-wide association dataset revealed that rs10012946, which is in strong linkage disequilibrium with the three WFS1 SNPs (r(2)=0.88-1.0), was associated with type 2 diabetes (allelic odds ratio 0.85, 95% CI 0.75-0.97, p=0.026). In the DPP, we noted a trend towards increased insulin secretion in carriers of the protective variants, although for most SNPs this was seen as compensatory for the diminished insulin sensitivity.

CONCLUSIONS/INTERPRETATION

The previously reported protective effect of select WFS1 alleles may be magnified by a lifestyle intervention. These variants appear to confer an improvement in beta cell function.

In pursuit of change: youth response to intensive goal setting embedded in a serious video game

BACKGROUND

Type 2 diabetes has increased in prevalence among youth, paralleling the increase in pediatric obesity. Helping youth achieve energy balance by changing diet and physical activity behaviors should decrease the risk for type 2 diabetes and obesity. Goal setting and goal review are critical components of behavior change. Theory-informed video games that emphasize development and refinement of goal setting and goal review skills provide a method for achieving energy balance in an informative, entertaining format. This article reports alpha-testing results of early versions of theory-informed goal setting and reviews components of two diabetes and obesity prevention video games for preadolescents.

METHOD

Two episodes each of two video games were alpha tested with 9- to 11-year-old youth from multiple ethnic groups. Alpha testing included observed game play followed by a scripted interview. The staff was trained in observation and interview techniques prior to data collection.

RESULTS

Although some difficulties were encountered, alpha testers generally understood goal setting and review components and comprehended they were setting personal goals. Although goal setting and review involved multiple steps, youth were generally able to complete them quickly, with minimal difficulty. Few technical issues arose; however, several usability and comprehension problems were identified.

CONCLUSIONS

Theory-informed video games may be an effective medium for promoting youth diabetes and obesity prevention. Alpha testing helps identify problems likely to have a negative effect on functionality, usability, and comprehension during development, thereby providing an opportunity to correct these issues prior to final production.