Behavioural implications of traditional treatment and closed-loop automated insulin delivery systems in Type 1 diabetes: applying a cognitive restraint theory framework.

As the prevalence of obesity in Type 1 diabetes rises, the effects of emerging therapy options should be considered in the context of both weight and glycaemic control outcomes. Artificial pancreas device systems will 'close the loop' between blood glucose monitoring and automated insulin delivery and may transform day-to-day dietary management for people with Type 1 diabetes in multiple ways. In the present review, we draw directly from cognitive restraint theory to consider unintended impacts that closed-loop systems may have on ingestive behaviour and food intake. We provide a brief overview of dietary restraint theory and its relation to weight status in the general population, discuss the role of restraint in traditional Type 1 diabetes treatment, and lastly, use this restraint framework to discuss the possible behavioural implications and opportunities of closed-loop systems in the treatment of Type 1 diabetes. We hypothesize that adopting closed-loop systems will lift the diligence and restriction that characterizes Type 1 diabetes today, thus requiring a transition from a restrained eating behaviour to a non-restrained eating behaviour. Furthermore, we suggest this transition be leveraged as an opportunity to teach people lifelong eating behaviour to promote healthy weight status by incorporating education and cognitive reappraisal. Our aim was to use a transdisciplinary approach to highlight critical aspects of the emerging closed-loop technologies relating to eating behaviour and weight effects and to promote discussion of strategies to optimize long-term health in Type 1 diabetes via two key outcomes: glycaemic control and weight management.

Implications of iron deficiency/anemia on the classification of diabetes using HbA1c.

BACKGROUND/OBJECTIVES: Nonglycemic factors like iron deficiency (ID) or anemia may interfere with classification of diabetes and prediabetes using hemoglobin A1c (HbA1c). However, few population-based studies of diabetes in areas with endemic ID/anemia have been conducted. We aimed to determine how mutually exclusive categories of ID alone, anemia alone and iron-deficiency anemia (IDA) were each associated with prediabetes and diabetes prevalence using fasting blood glucose (FBG) versus HbA1c in a population-based study of adults with endemic ID/anemia. SUBJECTS/METHODS: We used data from the China Health and Nutrition Survey, a longitudinal, population-based study across 228 communities within nine provinces of China. This analysis included 7308 adults seen in the 2009 survey aged 18-75 years. We used descriptive and covariate-adjusted models to examine relative risk of prediabetes and diabetes using FBG alone, HbA1c alone, HbA1c and FBG, or neither (normoglycemia) by anemia alone, ID alone, IDA or normal iron/hemoglobin. RESULTS: Approximately 65% of individuals with diabetes in our sample were concordantly classified with diabetes using both FBG and HbA1c, while 35% had a discordant diabetes classification: they were classified using either FBG or HbA1c, but not both. Fewer participants with ID alone versus normal iron/hemoglobin were classified with diabetes using HbA1c only. From covariate-adjusted, multinomial regression analyses, the adjusted prevalence of prediabetes using HbA1c only was 22% for men with anemia alone, but 13% for men with normal iron/hemoglobin. In contrast, the predicted prevalence of prediabetes using HbA1c only was 8% for women with ID alone, compared with 13% for women with normal iron/hemoglobin. CONCLUSIONS: These findings suggest potential misclassification of diabetes using HbA1c in areas of endemic ID/anemia. Estimating diabetes prevalence using HbA1c may result in under-diagnosis in women with ID and over-diagnosis in men with anemia.

Vitamin D in youth with Type 1 diabetes: prevalence of insufficiency and association with insulin resistance in the SEARCH Nutrition Ancillary Study.

AIMS: To determine the prevalence of plasma vitamin D (25-dihydroxyvitamin D) insufficiency in individuals with Type 1 diabetes and to determine the cross-sectional and longitudinal associations of plasma vitamin D with insulin resistance. METHODS: Participants from the SEARCH for Diabetes in Youth Study [n = 1426; mean age 11.2 years (sd 3.9)] had physician-diagnosed Type 1 diabetes [diabetes duration mean 10.2 months (sd 6.5)] with data available at baseline and follow-up (approximately 12 and 24 months after baseline). Insulin resistance was estimated using a validated equation. Cross-sectional and longitudinal multivariate logistic regression models were used to determine the association of plasma vitamin D with insulin resistance, adjusting for potential confounders. RESULTS: Forty-nine per cent of individuals had plasma vitamin D < 50 nmol/l and 26% were insulin resistant. In cross-sectional multivariate analyses, participants who had higher plasma vitamin D (65 nmol/l) had lower odds of prevalent insulin resistance than participants with lower plasma vitamin D (25 nmol/l) (odds ratio 0.70, 95% CI 0.57-0.85). This association was attenuated after additional adjustment for BMI z-score, which could be a confounder or a mediator (odds ratio 0.81, 95% CI 0.64-1.03). In longitudinal multivariate analyses, individuals with higher plasma vitamin D at baseline had lower odds of incident insulin resistance, but this was not significant (odds ratio 0.85, 95% CI 0.63-1.14). CONCLUSIONS: Vitamin D insufficiency is common in individuals with Type 1 diabetes and may increase risk for insulin resistance. Additional prospective studies are needed to determine the association between plasma vitamin D and insulin resistance, and to further examine the role of adiposity on this association.

Racial/ethnic health disparities in South Carolina and the role of rural locality and educational attainment.

BACKGROUND: The prevalence of selected health indicators were compared among the Catawba Indians, African Americans, and whites in South Carolina, considering the possible role of rural locality and education. METHODS: Catawba members were respondents of a 1998 survey (N = 808). Other South Carolina residents were respondents of the 1995-1997 Behavioral Risk Factor Survey (4,150 whites and 1,413 African Americans). Prevalence of cardiovascular disease, diabetes, hypertension, overweight, poor health, smoking, physical inactivity, and poor diet were compared among the racial/ethnic groups. Logistic regression analyses were conducted within strata of urban/rural locality and education to determine whether these factors were associated with the adverse health indicators. RESULTS: Both Catawba and African Americans had higher prevalence of diabetes, hypertension, overweight, poor health, physical inactivity, and poor diet than whites. In addition, prevalence of diabetes, poor health, smoking, and poor diet were higher among the Catawba than among African Americans. Restricting the analyses to comparisons within urban/rural locality had little effect, whereas restricting the analyses to comparisons by education level eliminated many of the disparities among those with low education. CONCLUSIONS: Prevalence of chronic disease and adverse health behavior are higher among the Catawba than among other residents of South Carolina, especially compared with white residents.

Behavioral and demographic correlates of diabetes, hypertension and overweight among the Catawba Indian Nation.

OBJECTIVE: In 1998, the Catawba Diabetes and Health Survey (CDHS) was conducted among adult members of the Catawba Indian Nation living in the Carolinas to determine the prevalence of diabetes and other health conditions, and to assess the population's health-related behaviors. DESIGN: A population-based sample of adult members of the Catawba Indian Nation (N = 633) were surveyed by telephone or in person regarding health status and health-related behaviors. Logistic regression was used to determine demographic and behavioral correlates of diabetes, hypertension, and overweight among the Catawba. RESULTS: Age-adjusted prevalence rates of self-reported diabetes, hypertension and overweight were 12.3%, 29.1%, and 63.8%, respectively. Older age was related to diabetes, hypertension, and overweight (P<.0001 each), and heavier weight status was related to diabetes (P = .026) and hypertension (P<.0001). Nearly 40% of the Catawba are physically inactive (29.5% men, 46.5% women). Physical inactivity was related to diabetes and hypertension among men only, and related to overweight among women only (P<.05 each). Current smoking was inversely related to overweight among men and women (P = .002). Dietary behavior was not associated with the health outcomes. CONCLUSION: Given the high rates of overweight and physical inactivity, reducing the rates of both may be very important for the health of the Catawba, considering their association with diabetes and hypertension.

Insulin secretion, obesity, and potential behavioral influences: results from the Insulin Resistance Atherosclerosis Study (IRAS).

BACKGROUND: This work was conducted to evaluate associations of insulin secretion with overall and central obesity, dietary fats, physical activity, and alcohol. METHODS: A frequently sampled intravenous glucose tolerance test (FSIGT) was used to assess acute insulin response to glucose (AIR) and insulin sensitivity (S(I)) among adult participants (n=675 with normal, NGT; n=332 with impaired glucose tolerance, IGT) in the Insulin Resistance Atherosclerosis Study (IRAS). Disposition index (DI) was calculated as the sum of the log-transformed AIR and S(I) to reflect pancreatic compensation for insulin resistance. Obesity was measured as body mass index (kg/m(2), BMI) and central fat distribution by waist circumference (cm). Dietary fat intake (total, saturated, polyunsaturated, oleic acid), physical activity, and alcohol intake were assessed by standardized interview. RESULTS: In unadjusted analyses, BMI and waist were each positively correlated with AIR among NGTs (r=0.26 and 0.23, respectively; p<0.0001) but correlations were weaker among the IGTs (r=0.10, NS; r=0.13, p<0.05 for BMI and waist, respectively). BMI and waist were inversely correlated with DI among NGTs (r=-0.13 and -0.20, respectively; p<0.0001) and among IGTs (r=-0.20 and -0.19, respectively, p<0.0001). Dietary fat variables were positively related, and alcohol was inversely related, to AIR among NGTs (p<0.01) but not among IGTs. With all factors considered simultaneously in a pooled analysis of IGTs and NGTs, waist, but not BMI, was positively associated with AIR (p<0.001) and inversely associated with DI (p<0.01). None of the behavioral variables were independently related to either outcome. CONCLUSION: Among non-diabetic patients, central obesity appears to be related to higher insulin secretion, but to lower capacity of the pancreas to respond to the ambient insulin resistance.

Associations between alcohol consumption and insulin sensitivity and cardiovascular disease risk factors: the Insulin Resistance and Atherosclerosis Study.

OBJECTIVE: Light-to-moderate alcohol consumption has been associated with reduced cardiovascular disease (CVD) mortality, which may be explained by increased insulin sensitivity (SI) and an improved lipoprotein and blood pressure profile. Prior research has shown improved SI with light-to-moderate alcohol intake even though somewhat imprecise measures of SI were used. RESEARCH DESIGN AND METHODS: Relationships between alcohol use and SI and CVD risk factors were assessed in a cross-sectional analysis of 1,196 white, African-American, and Hispanic men and women from the Insulin Resistance and Atherosclerosis Study (IRAS). Five categories of previous-year alcohol use (never, <0.5 drinks/day, 0.5-0.99 drinks/day, 1-2.99 drinks/day, and > or =3 drinks/day) and log SI + 1 (frequently sampled intravenous glucose tolerance test with Bergman minimal model analysis), log fasting insulin, log triglycerides, HDL cholesterol, and systolic/diastolic blood pressure were examined using analysis of variance. RESULTS: Univariate analysis showed an inverse U-shaped relationship between SI and alcohol intake, with a peak at the 0.5-0.99 drinks/day category. A U-shaped relationship was observed between fasting insulin and the lipid and blood pressure measures. After adjustment for demographic (clinic, sex, ethnicity, age), lifestyle (smoking, dietary energy/fat intake, physical activity), and physical (BMI, waist circumference) variables, the alcohol/insulin association was attenuated, but the association with lipids and blood pressure remained for high-intake categories. CONCLUSIONS: These data suggest that the enhanced SI associated with light-to-moderate alcohol consumption may be a function solely of a BMI and central adiposity profile more favorable to higher SI.

Validity and reproducibility of a food frequency interview in a Multi-Cultural Epidemiology Study.

PURPOSE: There is limited support for the validity and reproducibility of dietary assessment in culturally diverse populations. The goal of this study was to evaluate the comparative validity and reproducibility of a Food Frequency Questionnaire (FFQ) used in the observational, multi-cultural Insulin Resistance Atherosclerosis Study (IRAS). METHODS: Women (n = 186) were approximately equally distributed by ethnicity from one urban center (African Americans and non-Hispanic whites) and one rural center (Hispanics and non-Hispanic whites). The IRAS FFQ was modified from the National Cancer Institute Health Habits and History Questionnaire to include ethnic and regional foods. Validity was assessed by comparing dietary values, including supplements, obtained from the FFQ to the average intake estimated from a series of 8 24-hour dietary recalls collected by telephone over the same 1-year period. Reproducibility was assessed among women who reported no change in their usual diet (n = 133) by comparing data from the original IRAS FFQ (in-person) with the FFQ administered for the validity study (two to four years later, by telephone). RESULTS: Correlation coefficients for validity were statistically significant for most nutrients (mean r = 0.62 urban non-Hispanic white, 0.61 rural non-Hispanic whites, 0.50 African American, 0.41 Hispanic) and did not differ among subgroups of obesity or diabetes status. The median correlation coefficient for the total sample was 0.49. Correlations were lower for women with less than 12 years of education (mean r = 0.30; median r = 0.25). The lower correlations among Hispanics was largely explained by the lower educational attainment in that sample. For reproducibility, the mean correlation for nutrients evaluated was r = 0.62 (median r = 0.63) and did not differ for subgroups. CONCLUSIONS: Although educational attainment must be considered, the IRAS FFQ appears to be reasonably valid and reliable in a diverse cohort.

Antioxidant nutrient intake and diabetic retinopathy: the San Luis Valley Diabetes Study.

OBJECTIVE: Diabetic retinopathy (DR) is a major cause of visual impairment and blindness in adults. Antioxidant nutrients, such as vitamins C and E and beta-carotene, may be protective of some eye disorders, such as cataract and age-related macular degeneration, but a relationship between these nutrients and DR has yet to be defined. The purpose of this study was to examine the relation between dietary and supplement intakes of vitamins C, E, and beta-carotene and the risk of DR. DESIGN: Both cross-sectional and longitudinal data were collected from participants in the San Luis Valley Diabetes Study, including non-Hispanic white and Hispanic adults in southern Colorado. PARTICIPANTS: A total of 387 participants with type 2 diabetes completed at least 1 complete retinal examination and 24-hour dietary recall (including vitamin supplement use). MAIN OUTCOME MEASURES: Type 2 diabetes was defined according to World Health Organization criteria. DR was assessed by retinal photographs, using the Airlie House criteria to classify DR as none, background, preproliferative, or proliferative. Data for both eyes, from up to three clinic visits per participant, were used for analysis. Ordinal logistic regression analysis was used, taking advantage of multiple clinic visits by individual participants and observations from both eyes, to assess the risk for increased DR severity over time as a function of changes in intake of vitamin C, vitamin E, and beta-carotene. Six categories of intake for each nutrient (first to fourth quintiles and ninth and tenth deciles) were considered to ascertain any potential threshold effect. Analyses accounted for age, duration of diabetes, insulin use, ethnicity, glycated hemoglobin, hypertension, gender, and caloric intake. RESULTS: An increase over time in vitamin C intake from the first to ninth deciles was associated with a risk for increased severity of DR (odds ratio = 2.21, P = 0.01), although excess risk was not observed for the tenth decile or the second through fourth quintiles compared to the first quintile. Increased intake of vitamin E was associated with increased severity of DR among those not taking insulin (odds ratios = 2.69, 2.59, 3.33, 5.65, 3.79; P < 0.02, for an increase over time from the first to the second through fourth quintiles and ninth and tenth deciles, respectively). Among those taking insulin, increased intake of beta-carotene was associated with a risk for severity of DR (odds ratio = 3.31, P = 0.003, and 2.99, P = 0.002, respectively, for the ninth and tenth deciles compared to the first quintile). CONCLUSIONS: No protective effect was observed between antioxidant nutrients and DR. Depending on insulin use, there appeared to be a potential for deleterious effects of nutrient antioxidants. Further research is needed to confirm associations of nutrient antioxidant intake and DR.

Genetic and behavioral determinants of waist-hip ratio and waist circumference in women twins.

OBJECTIVES: This study examines genetic and behavioral determinants of waist-hip ratio (WHR) and waist circumference among women twins. RESEARCH METHODS AND PROCEDURES: Six hundred eighty participants from the second examination of the Kaiser-Permanente Women Twins Study (1989 to 1990) were included. Women ranged in age from 31 to 90 years, and included 59% monozygotic and 41% dizygotic twins. Heritabilities of WHR and waist circumference were estimated (range=0 to 1) using three different statistical methods. Linear regression models that adjusted for the lack of independence within twin pairs were used to assess associations between behavioral variables, WHR, and waist circumference. RESULTS: Age and body mass index-adjusted heritability estimates ranged from 0.36 to 0.61 for WHR and 0.72 to 0.82 for waist circumference. When considered individually, after adjusting for age and body mass index, all behavioral characteristics, except calorie-adjusted fat intake, were significantly (p<0. 10) associated with waist circumference and WHR. Greater central adiposity was associated with lower education, higher alcohol consumption, lower physical activity, current cigarette smoking, higher parity, and postmenopausal status without hormone replacement therapy. In multivariate models, these associations persisted, except neither educational attainment nor alcohol intake was significantly associated with waist circumference. In longitudinal analyses, both measures were positively associated with current or recent-past smoking; infrequent or inconsistent physical activity; and long-term, daily consumption of alcohol. DISCUSSION: These cross-sectional and longitudinal associations are consistent with genetic and behavioral predictors of waist circumference and WHR. Whereas the evidence for genetic influences is stronger for waist circumference, both body fat measures may be similarly influenced by the behavioral factors considered.

An epidemiologic review of dietary intake studies among American Indians and Alaska Natives: implications for heart disease and cancer risk.

PURPOSE: Dietary factors play an important role in the occurrence of heart disease and cancer. While American Indians and Alaska Natives (AIANs) have unique heart disease and cancer mortality profiles, little is known about the effect of diet on heart disease and cancer risk in these populations. This paper reviews existing nutritional intake data from adult AIANs, and considers the potential impact of diet on heart disease and cancer in these communities. METHODS: A review of the literature was conducted using the Medline database system and other reference materials. Studies documenting nutrient intakes only were included in this review. Studies were limited to those among healthy, non-pregnant adults. RESULTS: A total of twelve reports from 1959 to 1996 were found. Sample sizes for the studies ranged from 20 to 575 subjects. Most studies were done among women, and a variety of nutritional assessment techniques (24 hour recall, food frequency questionnaire, multiple-day food record) were used. Most studies also had limited nutrient intake data, especially for dietary fiber and vitamin E. The majority of studies reported moderately high intakes of fat and saturated fat, and low intakes of polyunsaturated fat and fiber. CONCLUSIONS: Based on the limited data, diet may play an important role in the heterogeneity of heart disease and cancer mortality in AIAN communities. More research is needed to assess the impact of diet on heart disease and cancer risk, including more longitudinal data, and data to assess the validity and reliability of traditional methods of dietary assessment.