Julie A. Marshall

Dietary Fat Predicts Conversion From Impaired Glucose Tolerance to NIDDM: The San Luis Valley Diabetes Study

OBJECTIVE To determine if dietary fat intake measured at a baseline exam in subjects with impaired glucose tolerance (IGT) predicted the subsequent development of non-insulin-dependent diabetes mellitus (NIDDM). RESEARCH DESIGN AND METHODS Based on an oral glucose tolerance test (OGTT) (World Health Organization criteria), we identified 134 eligible subjects with IGT from a geographically based sample of subjects with no prior history of diabetes. One to three years after the baseline exam, 123 subjects (92%) had a repeat OGTT. Diet was assessed by a 24-h diet recall reported before the baseline OGTT. RESULTS The mean percentage of energy eaten as fat was 43.4% in 20 people subsequently developing NIDDM compared with 40.6% in 43 people remaining IGT and 38.9% in 60 subjects who subsequently reverted to normal glucose tolerance. In comparing the 20 subjects who developed NIDDM with the 103 who remained IGT or normal, an increase in fat intake of 40 g/day was associated with an increase in risk of NIDDM of 3.4-fold (95% confidence interval [CI] 0.8–13.6) adjusted for energy intake, age, sex, ethnicity, and obesity. The odds ratio increased to sixfold (95% CI 1.2–29.8) after adjustment for fasting glucose, insulin, and 1-h insulin. CONCLUSIONS Fat consumption significantly predicts NIDDM risk in subjects with IGT after controlling for obesity and markers of glucose metabolism.

High saturated fat and low starch and fibre are associated with hyperinsulinaemia in a non-diabetic population: The San Luis Valley Diabetes Study

Summary A geographically based sample of 1069 Hispanic and non-Hispanic white persons aged 20–74 years, living in southern Colorado and who tested normal on an oral glucose tolerance test (World Health Organization criteria) were evaluated to determine associations of dietary factors with fasting serum insulin concentrations. Subjects were seen for up to three visits from 1984 to 1992. A 24-h diet recall and fasting insulin concentrations were collected at all visits. In longitudinal data analysis, lower age, female gender, Hispanic ethnicity, higher body mass index, higher waist circumference, and no vigorous activity were significantly related to higher fasting insulin concentrations. High total and saturated fat intake were associated with higher fasting insulin concentrations after adjusting for age, sex, ethnicity, body mass index, waist circumference, total energy intake and physical activity. Dietary fibre and starch intake were inversely associated with fasting insulin concentrations. No associations with fasting insulin concentrations were observed for monounsaturated fat, polyunsaturated fat, sucrose, glucose and fructose intake. Associations were similar in men and women and for active and inactive subjects, though associations of fibre and starch intake with insulin concentrations were strongest in lean subjects. These findings support animal studies and a limited number of human population studies which have suggested that increased saturated and total fat intake and decreased fibre and starch intake increase fasting insulin concentrations and may also increase insulin resistance. These findings, which relate habitual macronutrient consumption to hyperinsulinaemia in a large population, may have implications for studies attempting primary prevention of non-insulin-dependent diabetes mellitus. [Diabetologia (1997) 40: 430–438]

Diagnostic methods for peripheral arterial disease in the san luis valley diabetes study

Peripheral arterial disease (PAD) is a frequent complication of diabetes mellitus. In the first phase of the San Luis Valley Diabetes Study, diagnostic criteria for PAD were evaluated in 607 controls and 343 diabetics. Normal ranges, and the lowest 2.5 percentile of the distribution of ankle/arm systolic blood pressure ratios were derived from a non-diabetic subset of the population with a very low probability of PAD. From this subgroup, abnormal ankle/arm ratios were defined as less than: 0.94 at rest, 0.73 after exercise, and 0.78 after reactive hyperemia. Using these criteria, PAD was identified in 130 subjects from the study population of 950 (prevalence of 13.7%). In contrast, a history of intermittent claudication, or an absent pulse in the extremity were uncommon findings in the study population, and thus had a low sensitivity and positive predictive value for PAD diagnosed by vascular laboratory criteria. We conclude that vascular laboratory tests provide a useful, and objective means of determining the prevalence of PAD in a geographically-based population of diabetic and control subjects.

Collective efficacy in Denver, Colorado: Strengthening neighborhoods and health through community gardens

Community gardens are viewed as a potentially useful environmental change strategy to promote active and healthy lifestyles but the scientific evidence base for gardens is limited. As a step towards understanding whether gardens are a viable health promotion strategy for local communities, we set out to examine the social processes that might explain the connection between gardens, garden participation and health. We analyzed data from semi-structured interviews with community gardeners in Denver. The analysis examined social processes described by community gardeners and how those social processes were cultivated by or supportive of activities in community gardens. After presenting results describing these social processes and the activities supporting them, we discuss the potential for the place-based social processes found in community gardens to support collective efficacy, a powerful mechanism for enhancing the role of gardens in promoting health.

Admixture in the Hispanics of the San Luis Valley, Colorado, and its implications for complex trait gene mapping.

Hispanic populations are a valuable resource that can and should facilitate the identification of complex trait genes by means of admixture mapping (AM). In this paper we focus on a particular Hispanic population living in the San Luis Valley (SLV) in Southern Colorado.We used a set of 22 Ancestry Informative Markers (AIMs) to describe the admixture process and dynamics in this population. AIMs are defined as genetic markers that exhibit allele frequency differences between parental populations ≥30%, and are more informative for studying admixed populations than random markers. The ancestral proportions of the SLV Hispanic population are estimated as 62.7 ± 2.1% European, 34.1 ± 1.9% Native American and 3.2 ± 1.5% West African. We also estimated the ancestral proportions of individuals using these AIMs. Population structure was demonstrated by the excess association of unlinked markers, the correlation between estimates of admixture based on unlinked marker sets, and by a highly significant correlation between individual Native American ancestry and skin pigmentation (R2= 0.082, p < 0.001). We discuss the implications of these findings in disease gene mapping efforts.

The Influence of Social Involvement, Neighborhood Aesthetics, and Community Garden Participation on Fruit and Vegetable Consumption

OBJECTIVES We considered the relationship between an urban adult populations fruit and vegetable consumption and several selected social and psychological processes, beneficial aesthetic experiences, and garden participation. METHODS We conducted a population-based survey representing 436 residents across 58 block groups in Denver, Colorado, from 2006 to 2007. We used multilevel statistical models to evaluate the survey data. RESULTS Neighborhood aesthetics, social involvement, and community garden participation were significantly associated with fruit and vegetable intake. Community gardeners consumed fruits and vegetables 5.7 times per day, compared with home gardeners (4.6 times per day) and nongardeners (3.9 times per day). Moreover, 56% of community gardeners met national recommendations to consume fruits and vegetables at least 5 times per day, compared with 37% of home gardeners and 25% of nongardeners. CONCLUSIONS Our study results shed light on neighborhood processes that affect food-related behaviors and provides insights about the potential of community gardens to affect these behaviors. The qualities intrinsic to community gardens make them a unique intervention that can narrow the divide between people and the places where food is grown and increase local opportunities to eat better.

Validation of a survey instrument to assess home environments for physical activity and healthy eating in overweight children.

BackgroundFew measures exist to measure the overall home environment for its ability to support physical activity (PA) and healthy eating in overweight children. The purpose of this study was to develop and test the reliability and validity of such a measure.MethodsThe Home Environment Survey (HES) was developed to reflect availability, accessibility, parental role modelling, and parental policies related to PA resources, fruits and vegetables (F&V), and sugar sweetened drinks and snacks (SS). Parents of overweight children (n = 219) completed the HES and concurrent behavioural assessments. Children completed the Block Kids survey and wore an accelerometer for one week. A subset of parents (n = 156) completed the HES a second time to determine test-retest reliability. Finally, 41 parent dyads living in the same home (n = 41) completed the survey to determine inter-rater reliability. Initial psychometric analyses were completed to trim items from the measure based on lack of variability in responses, moderate or higher item to scale correlation, or contribution to strong internal consistency. Inter-rater and test-retest reliability were completed using intraclass correlation coefficients. Validity was assessed using Pearson correlations between the HES scores and child and parent nutrition and PA.ResultsEight items were removed and acceptable internal consistency was documented for all scales (α = .66–84) with the exception of the F&V accessibility. The F&V accessibility was reduced to a single item because the other two items did not meet reliability standards. Test-retest reliability was high (r > .75) for all scales. Inter-rater reliability varied across scales (r = .22–.89). PA accessibility, parent role modelling, and parental policies were all related significantly to child (r = .14–.21) and parent (r = .15–.31) PA. Similarly, availability of F&V and SS, parental role modelling, and parental policies were related to child (r = .14–36) and parent (r = .15–26) eating habits.ConclusionThe HES shows promise as a potentially valid and reliable assessment of the physical and social home environment related to a childs physical activity and eating habits.

Prevalence and Risk Factors of Diabetic Retinopathy in Non-Hispanic Whites and Hispanics With NIDDM: San Luis Valley Diabetes Study

Diabetic retinopathy (DR) is the leading cause of blindness in adults in the United States. Because photocoagulation can reduce the incidence of blindness from severe DR by ∼50%, it is important to identify people at increased risk for DR so that appropriate treatment can be accomplished. Use of populations at increased risk for diabetes may identify groups at increased risk for complications. A recent report from the San Antonio Heart Study showed that Mexican Americans were at greater risk for servere DR than non-Hispanic Whites. To compare the prevalence of DR between non-Hispanics and Hispanics in southern Colorado, 279 people with non-insulindependent diabetes mellitus (NIDDM) were identified, and retinal photographs identified the presence and severity of retinopathy. The worse eye was used to classify the severity of DR for each patient. Ninety percent of the subjects (166 Hispanics and 85 non-Hispanic Whites) were classified by retinopathy level. The duration-adjusted prevalence of any DR was 41.8% in Hispanics and 54.1% in non-Hispanic Whites. Severe DR (preproliferative and proliferative) occurred in 18.5% of the Hispanics and in 21.3% of the non-Hispanic Whites. The odds ratio for any DR, comparing Hispanics with non-Hispanic Whites adjusted for other risk factors, was 0.40 (95% confidence interval = 0.21, 0.76). Other risk factors for the presence of any retinopathy included use of exogenous insulin, increased duration of diabetes, younger age at diagnosis, increased glycosylated hemoglobin level, and increased systolic blood pressure. These data suggest that, compared with non-Hispanic Whites, Hispanics in Colorado may be at decreased risk for diabetic retinopathy.

Relationship Between Habitual Physical Activity and Insulin Levels Among Nondiabetic Men and Women: San Luis Valley Diabetes Study

Objective To determine whether higher levels of physical activity would be associated with lower fasting insulin and C-peptide levels in a free-living nondiabetic population. Research Design and Methods A cross-sectional study was conducted with a Hispanic and non-Hispanic white population of 442 men and 489 women with normal glucose tolerance (by World Health Organization criteria) in two rural Colorado counties. Total physical activity was assessed by a 7-day physical activity recall from which metabolic equivalents were estimated. Relationships between metabolic equivalents and fasting insulin and C-peptide were assessed while considering obesity, age, and other risk factors known to influence fasting insulin levels. Results Among all subjects, univariate analyses showed that higher activity levels were associated with lower mean fasting insulin and C-peptide levels (P < or equal to 0.05). Multiple linear regression showed that higher activity was significantly associated with lower values of log fasting insulin and C-peptide levels in men only (P < 0.001) independent of obesity, fat distribution, and age. Men in the highest tertile of activity had an adjusted mean fasting insulin level of 59.2 pM and fasting C-peptide level of 0.5 nM compared with a fasting insulin level of 72.7 pM and fasting C-peptide level of 0.6 mM for men in the lowest tertile of activity. The magnitude of the inverse association between activity and insulin was greatest in older rather than younger men. Physical activity was not associated with fasting insulin or C-peptide levels in women in the multivariate analyses. Conclusions Based on cross-sectional data, we conclude that higher levels of habitual physical activity are associated with lower fasting insulin and C-peptide levels in Hispanic and non-Hispanic white men.

Validation of a Food Frequency Questionnaire in Preschool Children

Background. Support for the validity of food frequency questionnaires (FFQ) in preschool children using parental report is limited. Methods. We obtained dietary information for 68 children age 1–3 years using three or four 24-hour recalls and a FFQ regarding the child’s diet covering one year from families in Denver, CO from 1997 to 1999. FFQs were completed by the parents, and recalls were collected via interviews with the parents and alternate caregivers, where applicable. Nutrient biomarkers were measured in the plasma of 38 of the children. All nutrients were adjusted for energy intake using residuals, and log-transformed where necessary. Results. Correlations (Pearson r) between the FFQ and the average of the recalls were 0.33 for protein, 0.41 for carbohydrate, 0.39 for fat, 0.42 for vitamin C, 0.27 for alpha-tocopherol, and 0.08 for total energy intake. We found no substantial changes in these correlations after stratification by whether or not meals and snacks were provided by caregivers other than the parents. The highest correlations (Spearman r) with biological measures were 0.51 between plasma ascorbic acid and FFQ vitamin C, and 0.48 between plasma and FFQ alpha-tocopherol. Conclusions. The FFQ shows mostly good agreements with multiple 24-hour recalls and biomarkers in preschool children. In addition, the validity of the FFQ using parental report does not appear to be compromised when there are meal providers in addition to the parents.