Incidence of distal symmetric (sensory) neuropathy in NIDDM. The San Luis Valley Diabetes Study

OBJECTIVE

To determine the incidence and risk factors for distal symmetric sensory neuropathy (DSN) in people with NIDDM.

RESEARCH DESIGN AND METHODS

Prospective follow-up was conducted from 1988 to 1992 on 231 people free of DSN during the baseline period 1984-1988 (mean follow-up, 4.7 years). Subjects with incident DSN (n = 66) were defined by any two of three criteria: 1) bilateral paresthesia in legs or feet; 2) bilateral decreased or absent ankle reflexes; and/or 3) bilateral decreased or absent cold temperature discrimination in feet. Of all 66 cases, 42 had one positive follow-up visit; 14 cases had 2 positive follow-up visits.

RESULTS

The overall incidence rate of DSN was 6.1 per 100 person-years (95% CI, 4.7-7.8). The rate for Hispanics (n = 164) and non-Hispanic whites (n = 67), adjusted for age, sex, and NIDDM duration, was 5.3 per 100 person-years (95% CI, 3.9-7.0) and 5.0 per 100 person-years (95% CI, 2.8-8.1), respectively. Adjusting for age and sex, higher glycohemoglobin level and lower C-peptide secretion were associated with increased DSN but were no longer predictive after accounting for duration of diabetes. Logistic regression models found significantly increased risk of DSN for insulin treatment, current smoking, and history of myocardial infarction. Duration was related to DSN incidence until insulin treatment was included. Other risk factors, including height, weight, family history of diabetes, peripheral vascular disease, hypertension, urinary albumin, protein:creatinine ratio, retinopathy, and alcohol use, were not significantly related to incident DSN.

CONCLUSIONS

Hispanic and non-Hispanic whites with NIDDM have similar risks of DSN. Current cigarette smoking and a history of myocardial infarction may represent independent risk factors for DSN in addition to glycemic control.

The prevalence of age-related maculopathy by geographic region and ethnicity. The Colorado-Wisconsin Study of Age-Related Maculopathy

OBJECTIVES

To determine the prevalence of age-related maculopathy (ARM) in a biethnic population and to determine if there are ethnic and/or geographic differences in the prevalence of ARM.

DESIGN

Prevalence data from 2 population-based studies, the San Luis Valley Diabetes Study (n = 1541, ages 21-74 years) and the Beaver Dam Eye Study (n = 3999, ages 43-74 years), were compared.

SETTING

Southern Colorado and central Wisconsin.

MAIN OUTCOME MEASURE

Color stereoscopic fundus photographs were graded for ARM using the Wisconsin Age-related Maculopathy Grading System. Similar questionnaire, laboratory, and clinical data on potential risk factors were available from both studies.

RESULTS

Late-stage ARM was significantly less frequent among Hispanics than non-Hispanic whites (NHW) in Beaver Dam (odds ratio [OR] = 0.07; 95% confidence interval [CI] = 0.01-0.49; Hispanics vs Beaver Dam NHW). The prevalence of any ARM was significantly lower among San Luis Valley NHW (10.4%) than Beaver Dam NHW (14.3%) (OR = 0.67; 95% CI = 0.50-0.91). This prevalence difference was not explained by any of the risk factors examined (smoking, cardiovascular disease, diabetes, alcohol consumption, etc). The 2 NHW groups reported different European heritages.

CONCLUSIONS

Late-stage ARM appeared to be rare among Hispanics but there was no ethnic difference in prevalence of any ARM. The 33% difference in risk among NHW by geographic location was not reduced when controlling for possible risk factors or confounders, suggesting that genetic heritage may be an important determinant of risk for ARM.

Haplotype analysis of two APOA1/MspI polymorphisms in relation to plasma levels of apo A-I and HDL-cholesterol

A common MspI polymorphism (G/A) in the promoter region of the APOA1 gene (-75 bp) has been shown to be associated with plasma apo A-I and HDL-C variation in several, but not all, studies. Recently another MspI polymorphic site (+/-) in the 5'region of APOA1 (+83 bp) has been identified which may also be relevant to HDL metabolism. This study was undertaken to elucidate the individual and combined effects of these two polymorphisms on plasma apo A-I and HDL-C levels in a cohort of 534 normoglycemic US Whites from the San Luis Valley, Colorado. Both polymorphisms were in strong linkage disequilibrium (P < 0.005); of the expected four haplotypes (G+, G-, A+, A-) the A- was not observed in this sample. Single site RFLP analysis revealed an independent and significant effect associated with each polymorphism on plasma apo A-I variation but not on HDL-C variation. Further analyses showed that the genotype effects of both polymorphisms were confined to non-smokers only. Haplotype analysis, combining both RFLPs, was more informative as this explained almost twice the amount of phenotypic variation in plasma apo A-I compared to single RFLP analysis in non-smokers. Compared to the most common haplotype (G+), the A+ and G- haplotypes were associated with increased plasma apo A-I levels by 6.7 mg/dl and 22.0 mg/dl, respectively in non-smoking men, and by 4.6 mg/dl and 15.1 mg/dl in non-smoking women, respectively. These data indicate that haplotype analysis in this region may be important to elucidate the functional significance of the APOA1 gene in HDL metabolism.

Self-rated health among Hispanic vs non-Hispanic white adults: the San Luis Valley Health and Aging Study

OBJECTIVES

This study investigated whether objective health indicators explained lower self-rated health among Hispanics compared with non-Hispanic Whites. It also considered socioeconomic and cultural explanations.

METHODS

Health ratings of 429 Hispanics and 583 non-Hispanic Whites aged 20 through 74 were analyzed with logistic regression.

RESULTS

Illness indicators were found to be strongly correlated with self-rated health in both ethnic groups, but after such markers were controlled for, Hispanics remained 3.6 times more likely to report fair or poor health (95% confidence interval = 2.4, 5.3). Adjustment for socioeconomic factors accounted for a portion of Hispanics' lower health rating, but the strongest explanatory factor was acculturation.

CONCLUSIONS

Because of cultural and economic influences on definitions of health, ethnic differences in self-assessed health may not accurately reflected patterns resulting from objective health measurements.

Insulin sensitivity and abdominal obesity in African-American, Hispanic, and non-Hispanic white men and women. The Insulin Resistance and Atherosclerosis Study

Increased abdominal obesity has been related to lower insulin sensitivity (SI), independent of overall obesity, but it has been suggested that this relationship may be weaker in non-whites. In the Insulin Resistance and Atherosclerosis Study (IRAS), SI was estimated using a minimal model analysis of the frequently sampled intravenous glucose tolerance test in 1,625 men and women aged 40-69 years. Subjects included African-Americans, Hispanics, and non-Hispanic whites from Oakland and Los Angeles, CA, San Antonio, TX, and the San Luis Valley, CO. Minimum waist circumference was significantly (P = 0.0001) associated with SI after adjusting for age, sex, height, BMI, glucose tolerance status, ethnicity, and clinic. This relationship was significantly (P = 0.0001) stronger in subjects with normal glucose tolerance (NGT) (beta = -0.030, P = 0.0001) than in those with impaired glucose tolerance (IGT) (beta = -0.010, P = 0.02; NIDDM: beta = -0.013, P = 0.0001). There were no significant ethnic differences in effect size across the spectrum of glucose tolerance. Waist circumference was also positively related to fasting insulin, an indirect measure of insulin sensitivity, in NGT (P = 0.0001), IGT (P = 0.0003), and NIDDM (P = 0.0002). The waist-fasting insulin relationship was significantly weaker in African-Americans, relative to non-Hispanic whites, in NGT and IGT (tests of statistical interaction: P = 0.04 and P = 0.02, respectively). In general, these patterns were similar in models specifying waist-to-hip ratio (WHR), rather than waist circumference, as the independent variable. While some ethnic variability exists, a negative relationship between abdominal obesity and insulin sensitivity was confirmed for all three ethnic groups across the spectrum of glucose tolerance.

Population screening for glucose intolerant subjects using decision tree analyses

The purpose of this study was to develop a method of screening for impaired glucose tolerance and previously undiagnosed NIDDM that could be used preliminary to the administration of an oral glucose tolerance test (OGTT) for final classification of glucose tolerance status. The purpose of a preliminary screening of this type would be to reduce the number of OGTT's needed to identify cases of IGT and NIDDM in the population. We used NIDDM risk indicators and decision tree analysis methods (CART software) to identify subgroups of the population at increased risk. We examined a population of Hispanic (n = 583) and non-Hispanic white (n = 768) subjects without a prior history of diabetes. Subjects were classified as normal, IGT or NIDDM (WHO criteria) based on results from a 75 g oral glucose tolerance test (OGTT). Sensitivity (SEN) and specificity (SPE) of the CART models were calculated using the OGTT as the 'gold standard.' Two approaches to screening were simulated. In the simultaneous approach all risk variables were entered into CART models at once. In the serial approach, risk variables were grouped according to degree of effort required for data collection, and were entered into CART models in stages. Fasting glucose, age and body mass index (BMI) were selected as risk variables by CART when simulating the simultaneous approach (SEN = 91%, SPE = 55%). In the serial approach, CART used age and BMI to eliminate 35% of the population from further screening, and then used fasting glucose, glycohemoglobin, age and BMI to classify the remaining higher risk subjects (SEN = 85%, SPE = 64%). These models suggest that screening for IGT and previously undiagnosed NIDDM can be based on measurement of relatively simple indicators, and yet maintain a level of both sensitivity and specificity acceptable for this type of preliminary screening.

Lack of association between early exposure to cow's milk protein and beta-cell autoimmunity. Diabetes Autoimmunity Study in the Young (DAISY)

OBJECTIVE

To examine whether infant dietary exposure to cow's milk is associated with beta-cell autoimmunity (BCA), an early predictor of insulin-dependent diabetes mellitus (IDDM).

SETTING

Denver, Colo.

DESIGN

Cross-sectional with retrospective analysis.

PARTICIPANTS

Between January 1994 and December 1995, 253 children from 171 families of persons with IDDM were screened for BCA. All children were between the ages of 9 months and 7 years.

MAIN OUTCOME MEASURES

BCA was defined as elevated levels of insulin autoantibody, glutamic acid decarboxylase autoantibody, or insulinoma-associated islet tyrosine phosphatases autoantibody (IA-2) above the 99th percentile of 198 normal subjects.

RESULTS

Eighteen cases of BCA were detected; 153 unrelated autoantibody-negative children were selected from the cohort as controls. There were no differences in the proportion of cases and controls who were exposed to cow's milk or foods containing cow's milk or to cereal, fruit and vegetable, or meat protein by 3 months or by 6 months of age. Children with BCA were breast-fed for a slightly longer duration than controls (median duration 10 vs 8 months, P=.07).

CONCLUSIONS

These data suggest that early exposure to cow's milk or other dietary protein is not associated with BCA. This calls into question the importance of cow's milk avoidance as a preventive measure for IDDM.

Newborn screening for HLA markers associated with IDDM: diabetes autoimmunity study in the young (DAISY)

Autoimmunity causing insulin-dependent diabetes mellitus (IDDM) begins in early childhood due to interactions between genes and unknown environmental factors that may be identified through follow-up of a large cohort of genetically susceptible children. Such a cohort has been established using a simple and rapid cord blood screening for HLA alleles. The DRB1 and DQB1 second exon sequences were co-amplified using the polymerase chain reaction and hybridized with single and pooled sequence-specific oligonucleotide probes. Four individual probes were used to detect the susceptibility alleles DRB1*03, DRB1*04, and DQB1*0302 as well as the usually protective DRB1*15/16 (DR2) alleles. In addition, pooled probes allow the distinction of DR3/3 from the DR3/x genotype (where x is neither DR2, 3, nor 4) and DR4/4 from DR4/x. Among 5000 newborns from the general Denver population, we have found the high-risk genotype (DRB1*03/ DRB1*04, DQB1*0302) to be present in 2.4% of non-Hispanic whites, 2.8% of Hispanics, and 1.6% of African Americans. The moderate-risk genotypes (DRB1*04, DQB1*0302/DRB1*04, DQB1*0302, DRB1*04, DQB1*0302/x, or DRB1*03/DRB1*03) are present in 17% of American non-Hispanic whites, 24% of Hispanics and in 10% of African Americans. These results demonstrate the feasibility of a large-scale newborn screening for genes associated with IDDM. The ultimate role for such a screening in future routine prediction and prevention of IDDM will depend on the availability of an effective and acceptable form of clinical intervention.

Beta-cell autoantibodies in infants and toddlers without IDDM relatives: diabetes autoimmunity study in the young (DAISY)

Little is known concerning the natural history of beta-cell autoimmunity in infants and toddlers, especially in those without a first degree IDDM relative. A population-based cohort of Colorado infants at increased IDDM risk due to their HLA genotype has been identified through a PCR-based HLA screening of cord blood and is being prospectively studied. We report the distribution of insulin (IAA), GAD65 (GAA), and ICA512 autoantibody levels in 312 children aged 9 months and in 131 children aged 15 months from this cohort, without family history of IDDM. The levels of IAA, GAA and ICA512 did not differ by the HLA genotype (DR3/4,DQB1*0302 vs. DR3/3, vs. DR2/DR4,DQB1*0302 vs. DRx/4,DQB1*0302, where x is not DR3 or DR2), by ethnicity (non-Hispanic whites vs. other ethnic groups), or by age (9 vs. 15 months). The 95th and 99th percentiles of the IAA distribution were respectively 40 and 61 nU/ml at the age of 9 months and 38 and 59 nU/ml at the age of 15 months. The 95th and 99th percentiles of the GAA distribution were respectively 0.020 and 0.046 at the age of 9 months and 0.022 and 0.098 at the age of 15 months. We propose to use IAA levels greater than 60 nU/ml and GAA index greater than 0.05 to define the presence of beta-cell autoimmunity in children younger than 2 years.

Increased insulin resistance and insulin secretion in nondiabetic African-Americans and Hispanics compared with non-Hispanic whites. The Insulin Resistance Atherosclerosis Study

The etiology of NIDDM is still controversial, with both insulin resistance and decreased insulin secretion postulated as potential important factors. African-Americans and Hispanics have a two- to threefold excess risk of developing NIDDM compared with non-Hispanic whites. Yet little is known concerning the prevalence of insulin resistance and secretion defects in minorities, especially in African-Americans in population-based studies. Fasting and 2-h post-glucose load glucose and insulin levels, insulin-mediated glucose disposal (insulin sensitivity index) (S(I)), glucose effectiveness (S(G)), and first-phase insulin response (acute insulin response [AIR]) were determined in nondiabetic African-Americans (n= 288), Hispanics (n= 363), and non-Hispanic whites (n= 435) as part of the Insulin Resistance Atherosclerosis Study. Subjects received a standard 2-h oral glucose tolerance test on the first day and an insulin-modified frequently sampled intravenous glucose tolerance test on the second day. African-Americans and Hispanics were more obese than non-Hispanic whites. Both African-Americans and Hispanics had higher fasting and 2-h insulin concentrations and AIR but lower S(I) than non-Hispanic whites. No ethnic difference was observed in S(G). After further adjustments for obesity, body fat distribution, and behavioral factors, African-Americans continued to have higher fasting and 2-h insulin levels and AIR, but lower S(I) than non-Hispanic whites. In contrast, after adjustment for these covariates, no significant ethnic differences in S(I) or fasting insulin levels were observed between Hispanics and non-Hispanic whites. Hispanics continued to have higher 2-h insulin levels and AIRs than those in non-Hispanic whites. In this report, the association between S(I) and upper body adiposity (waist-to-hip, ratio) was similar in each ethnic group. Both nondiabetic African-Americans and Hispanics have increased insulin resistance and higher AIR than nondiabetic non-Hispanic whites, suggesting that greater insulin resistance may be in large part responsible for the higher prevalence of NIDDM in these minority groups. However, in Hispanics. the greater insulin resistance may be due to greater adiposity and other behavioral factors.

Hypertension among rural Hispanics and non-Hispanic whites: the San Luis Valley Diabetes Study

IN THE SAN LUIS VALLEY DIABETES STUDY (SLVDS) researchers studied hypertension morbidity and risk factors in 1788 Hispanics and non-Hispanic whites (NHW) from the rural San Luis Valley in Colorado. Hypertension was defined by The Fifth Report of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure (JNC-V) criteria. In this population-based study, the prevalence, incidence, and risk factors for hypertension did not differ significantly between non-diabetic Hispanics and NHW participants. Hypertension risk increased with age, heart rate, serum triglycerides, insulin area, and obesity (in young participants). Compared with the prevalence rates in non-diabetic participants, the rates were significantly higher in people with diabetes and increased with the duration of diabetes and central obesity. The risk of hypertension in diabetic Hispanics appeared to be somewhat lower than that in NHW diabetics.

Associations between dietary factors and serum lipids by apolipoprotein E polymorphism

A geographically based observational study of 852 nondiabetic Hispanic and non-Hispanic white persons in southern Colorado aged 20-74 y was conducted to determine whether diet-lipid associations were modified by the apolipoprotein E (apoE, protein; APOE, gene) polymorphism. Subjects were seen for up to three visits from 1984 to 1992. A 24-h diet recall was collected and fasting serum lipid concentrations were measured at all visits. In longitudinal-regression analyses, dietary factors were significantly associated with serum lipid concentrations in the directions expected based on the large amount of literature on this topic. The positive relation between dietary cholesterol and serum total and low-density-lipoprotein cholesterol was strongest in Hispanic subjects with the APOE*2 allele (E2/ 2,3/2 genotypes) and non-Hispanic white subjects with the APOE*3 allele (E3/3 genotype), and there was no association in subjects with the APOE*4 allele (E4/3, 4/4 genotypes) in either ethnic group. No other statistically significant differences in the relations between dietary factors and serum lipid concentrations by APOE polymorphism were identified. These findings suggest that the APOE polymorphism plays only a minor role in modifying the association between dietary factors and serum lipids.

Exploration of simple insulin sensitivity measures derived from frequently sampled intravenous glucose tolerance (FSIGT) tests. The Insulin Resistance Atherosclerosis Study

Both abnormal insulin levels and low insulin sensitivity have been implicated as risk factors for Type II diabetes mellitus and cardiovascular disease. While insulin level is relatively simple to assess, direct measurement of insulin sensitivity is much more invasive, costly, and time-consuming. The authors considered eight previously described measures or indices of indices of insulin sensitivity derived from the frequently sampled intravenous glucose tolerance test (FSIGT). Each one was evaluated by strength and consistency of association with insulin sensitivity computed from glucose clamp (SI(clamp)), across three glucose tolerance groups, including participants with normal glucose tolerance (n = 11), impaired glucose tolerance (n = 20), and non-insulin-dependent diabetes mellitus (n = 24). Minimal model analysis (MINMOD SI(22)), based on the 22-sample FSIGT, performed best based on statistical criteria of strong and consistent association with SI(clamp). An insulin sensitivity measure similar to that of Galvin et al. (Diabetic Medicine 1990;9:921-8), defined as glucose disappearance (10-50 minutes) divided by insulin area under the curve above baseline from 0-50 minutes, performed best based on statistical criteria and time-savings. Galvin insulin sensitivity is simple to calculate, requires only a 50-minute FSIGT, and is significantly (p < 0.001) and not inconsistently (p = 0.12 for inconsistent association) associated with SI(clamp) over a wide range of glucose tolerance.

Association of education level with atherogenic diets in a rural biethnic population

Better definition of dietary intakes among subpopulations will facilitate the implementation of relevant public health interventions. This study describes total calorie and macronutrient intake by level of education as reported by Hispanic and non-Hispanic white persons in the rural San Luis Valley of southern Colorado. Current diet was assessed for a geographically based sample of 552 Hispanic and 754 non-Hispanic white (NHW) adults 30-74 years of age in two counties of rural southern Colorado 1984-1988). Diet was assessed by 24-hour recall. Hispanic men and women reported lower total calorie intakes at all ages than NHWs; however, the macronutrient composition was similar between groups (38.5% and 46.0% of calories from fat and carbohydrate, respectively). Ethnic differences in body size and reported physical activity did not account for ethnic differences in reported calorie intake. In both ethnic groups, subjects with more education reported higher calorie intake and less atherogenic diets (lower total fat, saturated fat, cholesterol, and Keys Index; higher polyunsaturated fat, P/S ratio, and total carbohydrate). In Hispanics and NHWs, lower education groups may require targeted interventions to decrease total fat, saturated fat, and cholesterol. Further study is needed to understand the ethnic difference in reported calorie intake.

Ethnic differences in micronutrient intake in a rural biethnic population

Differences in micronutrient intake have been observed between populations of differing socioeconomic status (SES) and ethnicity. This study reports micronutrient intake among Hispanic and non-Hispanic white (NHW) persons in the rural San Luis Valley of southern Colorado. Current diet was assessed for a geographically based sample of 552 Hispanic and 754 NHW adults 30-74 years of age in two counties of rural southern Colorado (1984-1988). Diet was assessed by 24-hour recall. NHWs reported higher mean calorie intakes than Hispanics of both genders. NHWs had greater intakes of calcium, magnesium, potassium, phosphorus, riboflavin, niacin, zinc, vitamin A, and vitamin C than Hispanics, after accounting for ethnic differences in gender, age, and calorie intake. Differences in intake by gender were observed within and between ethnic groups. After adjusting for gender, age, ethnicity, and calories, we observed no statistically significant trends by SES measures. We conclude that diets of Hispanic adults would benefit from the addition of fresh fruits, vegetables, and high-calcium foods.

Relationship between habitual physical activity and insulin area among individuals with impaired glucose tolerance. The San Luis Valley Diabetes Study

OBJECTIVE

To determine whether higher levels of physical activity are associated with lower fasting insulin levels and lower insulin areas under the oral glucose tolerance curve in individuals with impaired glucose tolerance (IGT) in a community setting.

RESEARCH DESIGN AND METHODS

Data from a cross-sectional study of a population consisting of 219 Hispanic and non-Hispanic white men and women with IGT (by World Health Organization criteria) in two rural Colorado counties were analyzed. Total physical activity was assessed by a 7-day physical activity recall, from which metabolic equivalents (METs) were estimated (expressed as MET h/week). Relationships of MET h/week with fasting insulin levels and insulin areas were assessed while considering obesity, age, and other risk factors known to influence fasting insulin level and insulin area.

RESULTS

Among all subjects, univariate analyses showed that higher physical activity levels were associated with lower mean insulin areas and fasting insulin levels (both P < 0.05). Multiple linear regression showed that higher levels of physical activity were significantly associated with lower values of of the insulin area (P < 0.001) but not with fasting insulin levels. The relationship between insulin area and habitual physical activity was independent of obesity, fat distribution, and age.

CONCLUSIONS

On the basis of cross-sectional data, we conclude that higher levels of habitual physical activity are associated with lower insulin areas in a population of individuals with IGT. Understanding the impact of physical activity on markers of insulin action in individuals with IGT is important because of the greatly enhanced risk of non-insulin-dependent diabetes mellitus and, hence, cardiovascular disease in this population.

Effect of diagnostic criteria on the prevalence of peripheral arterial disease. The San Luis Valley Diabetes Study

BACKGROUND

The ankle/brachial systolic blood pressure index (ABI), a noninvasive measure of peripheral arterial disease (PAD), is widely used in epidemiological studies. However, the normal ranges of the ABI in healthy populations and ABI criteria for the diagnosis of PAD in large population studies have not been critically evaluated.

METHODS AND RESULTS

The San Luis Valley Diabetes Study (SLVDS) was designed to evaluate the prevalence and complications of non-insulin-dependent diabetes mellitus (NIDDM) in a biethnic population. The present study was conducted as part of the SLVDS to assess the prevalence of vascular disease in 1280 nondiabetic control subjects and 430 patients with NIDDM. The ABI criteria for PAD were developed in 403 healthy individuals with a low risk for cardiovascular disease. In these low-risk subjects, the average resting ABI value was 0.07 lower in women than in men. In both sexes, the dorsalis pedis ABI was 0.04 lower than in the posterior tibial artery, and the left leg ABI was 0.02 lower than the right leg ABI (all differences, P < .05). In the low-risk subjects, ABI values were lower after exercise than at rest and had similar differences by sex and leg as observed at rest. Using specific abnormal cutoff points for the ABI, we evaluated three criteria for PAD in the overall population: two abnormal vessels in the same leg at rest (both dorsalis pedis and posterior tibial arteries), one abnormal vessel per leg at rest, and an ABI abnormality only after exercise. Subjects classified with PAD by the two-vessel criterion had a higher frequency of claudication and the physical finding of an absent pulse compared with subjects without PAD or patients with PAD defined by the one-vessel or exercise criterion. Use of the two-vessel criterion identified an increased risk of PAD with increasing age, NIDDM, smoking, hypertension, and elevated cholesterol levels. In contrast, the one-vessel PAD criterion was associated only with increasing age and smoking, and exercise-diagnosed PAD was not associated with any cardiovascular risk factor except for male sex.

CONCLUSIONS

In low-risk subjects, the normal distribution and lower abnormal cutoff point values of the ABI differed by type of test, sex, ankle vessel, and leg. When these specific abnormal cutoff points were applied to the SLVDS population, the two-vessel abnormal criterion described patients with typical clinical characteristics of PAD and the expected associations of PAD with cardiovascular risk factors. These clinical characteristics and cardiovascular risk factor associations were less evident with PAD diagnosed by the one-vessel or exercise criterion. Therefore, an abnormal dorsalis pedis and posterior tibial ABI in the same leg at rest should be used for the diagnosis of PAD in epidemiological studies.

High fasting insulin levels associated with lower rates of weight gain in persons with normal glucose tolerance: the San Luis Valley Diabetes Study

OBJECTIVE

to investigate whether increased insulin resistance is associated with a reduced risk of weight gain among Hispanic and non-Hispanic white persons in Colorado.

DESIGN

measurements were taken at baseline and after an average of 4.3 years.

SUBJECTS

789 normal glucose tolerant subjects 20 to 74 years of age were studied.

MEASUREMENTS

fasting insulin levels were used as an indirect marker of insulin resistance.

RESULTS

the average baseline body mass index (BMI) was 26.1 (+/- 3.6 s.d.) in men and 25.2 (+/- 4.4 s.d.) in women. The average weight change at follow-up was 0.8 kg (+/- 4.3 s.d.) in men and 1.3 kg (+/- 5.0) in women. A doubling in initial fasting insulin was associated with a reduced risk of gaining 5 kg (n = 134) and 10 kg (n = 24) of weight in logistic regression models (OR5kg = 0.76, 95% CI: 0.59, 0.99 and OR10kg = 0.61, 95% CI: 0.36, 1.02). Similarly, a doubling of initial fasting insulin was associated (P = 0.006) on average with a 6.3 kg less weight gain in linear regression models, independently of initial body weight, age, sex, ethnicity and BMI. The relation was consistently observed in men and women and in both ethnic groups.

CONCLUSION

higher initial fasting insulin decreases the risk of subsequent weight gain in both Hispanic and non-Hispanic white normal glucose tolerant individuals similar to Pima Indians. This appears to be a common biologic characteristic in moderate to low as well as high risk populations for NIDDM.

The relationship of APOE polymorphism and cholesterol levels in normoglycemic and diabetic subjects in a biethnic population from the San Luis Valley, Colorado

We have determined apolipoprotein E (apoE = protein, APOE = gene) polymorphism and its relationship with total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C) and triglyceride levels in normoglycemic Hispanics (n = 446) and non-Hispanic whites (NHWs) (n = 659) as well as in diabetic Hispanics (n = 235) and NHWs (n = 116) from the San Luis Valley, Colorado. Effects were estimated separately for each group, and within each group men and women were analyzed separately; women were further categorized into pre- and post-menopausal status. The distribution of the APOE genotype pattern was comparable between the NHW normoglycemics and diabetics but it was significantly different among Hispanic normoglycemics and diabetics (P < 0.005). In the normoglycemic sample the APOE allele frequencies were significantly different between the two ethnic groups: the APOE*2 (0.09 vs. 0.05; P < 0.01) and APOE*4 (0.15 vs. 0.09; P < 0.002) allele frequencies were higher while the APOE*3 (0.76 vs. 0.86; P < 0.0001) allele frequency was lower in NHWs than in Hispanics. Significant variability among the three common APOE genotypes (3-2, 3-3, and 4-3) was observed for TC and LDL-C in normoglycemic Hispanic women (P = 0.09 and P = 0.03) but not in Hispanic men. In normoglycemic NHWs, however, significant mean differences among APOE genotypes were observed for TC and LDL-C in both women (P < 0.0001 and P < 0.0001) and men (P = 0.009 and P = 0.01). In Hispanic females, the APOE polymorphism accounted for 5.6% and 7.6% of the phenotypic variance for TC and LDL-C, respectively. In NHW females, the APOE polymorphism explained 10.2% of the phenotypic variance for TC and LDL-C, and in NHW males these values were 6.2% and 7.5%, respectively. There was no evidence of physiologic interaction between the APOE polymorphism and menopause status in affecting TC and LDL-C in NHW women (P = 0.65 and P = 0.55) but a suggestion of interaction was observed in Hispanic women for TC and LDL-C (P = 0.11 and 0.07). After the Hispanic women were stratified into pre- and postmenopausal groups, the effect of the APOE polymorphism on TC and LDL-C was significant only in the premenopausal group. Among diabetics, no significant effect of the APOE polymorphism was seen on cholesterol levels.(ABSTRACT TRUNCATED AT 400 WORDS)

ApoA-IV polymorphism associated with myocardial infarction in obese NIDDM patients. The San Luis Valley Diabetes Study

Non-insulin-dependent diabetes mellitus (NIDDM) confers myocardial infarction (MI) risk unexplained by known factors. In 356 NIDDM patients and 1,087 people with normal glucose tolerance, we investigated the association between MI risk and polymorphism at codon 360 in the apolipoprotein A-IV (apoA-IV) gene. During 1984-1992, MI was diagnosed in 84 diabetic and in 106 nondiabetic people. The risk of MI did not differ by apoA-IV phenotype in nondiabetic people; however, in NIDDM patients, those with the apoA-IV 1-2 phenotype had 2.8 (95% confidence interval: 1.4-5.6) higher MI risk than those with the 1-1 phenotype, adjusting for age, gender, ethnicity, hypertension, smoking, body mass index, fat centrality, and low-density lipoprotein and high-density lipoprotein cholesterol. The risk of MI was particularly high in obese NIDDM patients with the apoA-IV 1-2 phenotype: 5.1 (2.4-11.2) times that in obese apoA-IV 1-1 NIDDM patients and 7.7 (3.6-16.7) times that in lean nondiabetic people. The effect of apoA-IV 1-2 did not appear to be a part of the insulin-resistance syndrome nor was it dependent on diabetes duration or control. One half of the excess MI risk in the diabetic population studied was explained by the apoA-IV 1-2 phenotype. These results indicate that approximately 17% of NIDDM patients have a high MI risk apoA-IV phenotype that is particularly deleterious in obese patients.

Birth prevalence of cleft lip and palate in Colorado by sex distribution, seasonality, race/ethnicity, and geographic variation

An epidemiologic study was designed to describe the association of potential risk factors with the occurrence of cleft lip and palate (CL/P) births in Colorado for the years 1982-1988. There were 307 children out of 381,175 live births identified, through birth certificate data, with a diagnosis of cleft palate or cleft lip with or without cleft palate. For this period, the birth prevalence was 0.81/1000. Male gender [odds ratio (OR) = 1.62, 95% confidence interval (CI) = 1.28, 2.04], white race (OR = 2.87, 95% CI = 1.52, 5.44), and non-metropolitan residence (OR = 1.59, 95% CI = 1.23, 2.05) were each associated with an excess risk of having a cleft abnormality of any type at birth. No differences in the occurrence of cleft lip and palate were observed by month of birth, altitude of county of residence, or in Hispanic compared with non-Hispanic newborns. Using information from the 1989 Colorado Registry for Children with Special Needs, there was little evidence of ascertainment bias on major factors of interest for the birth certificate data. Further studies are required to define the factors associated with excess risk of CL/P in non-metropolitan areas.

Risk factors for distal symmetric neuropathy in NIDDM. The San Luis Valley Diabetes Study

OBJECTIVE

To investigate risk factors for distal symmetric (sensory) neuropathy among prevalent cases of non-insulin-dependent diabetes mellitus (NIDDM) in a population-based study in southern Colorado.

RESEARCH DESIGN AND METHODS

Prevalent neuropathy was identified in 77 of 277 people with NIDDM by a standardized history and neurologic examination. Fifteen known or suspected risk factors for neuropathy were determined without knowledge of neuropathy status.

RESULTS

Older age at examination, longer duration of diabetes, higher glycohemoglobin percentage, lower fasting C-peptide, insulin use, and presence of retinopathy and nephropathy (microalbumin > or = 200 micrograms/ml) were all significantly associated with neuropathy. Sex, ethnicity (Hispanic versus non-Hispanic white), height, systolic blood pressure, peripheral vascular disease, cigarette and alcohol use, and serum lipid levels were not significantly associated with neuropathy. In a multivariate logistic model, increasing age (odds ratio [OR] = 1.3, 95% confidence interval [CI] = 1.1-1.6), longer duration of diabetes (OR = 1.3, CI = 1.0-1.6), increased glycohemoglobin percentage (OR = 1.5, CI = 1.1-2.1), and insulin use (OR = 2.8, CI = 1.3-6.1) were associated with neuropathy. Retinopathy (OR = 3.0, CI = 1.2-7.7), but not nephropathy, was important when added to this model.

CONCLUSIONS

Worse glycemic control and insulin use were independently associated with neuropathy in people with NIDDM. Whether insulin use represents another marker for severity of the metabolic disturbance or is an independent risk factor for neuropathy requires further study. We could not confirm associations of neuropathy with height, with nephropathy, or with retinopathy, independent of duration of diabetes.

Patterns and predictors of hypertension incidence among Hispanics and non-Hispanic whites: the San Luis Valley Diabetes Study

OBJECTIVES

To determine whether Hispanics are at lower risk for the development of hypertension than non-Hispanic Whites. We also examined selected predictors of hypertension incidence and explored the role of markers of insulin resistance in the development of hypertension.

DESIGN

A cohort study of a geographically-based sample of Hispanic and non-Hispanic white southern Colorado residents who were re-examined an average of 4 years after their baseline examination.

METHODS

These analyses included 664 participants who were normotensive and confirmed nondiabetic by an oral glucose tolerance test at their baseline examination. Hypertension was defined as systolic blood pressure > or = 140 mmHg or diastolic blood pressure > or = 90 mmHg or use of antihypertensive medication.

RESULTS

Hispanics and non-Hispanic Whites had similar hypertension incidence rates. The strongest predictors of hypertension incidence were baseline blood pressure and age. Higher baseline heart rates and higher body mass index also predicted hypertension. Increased fasting insulin levels were associated with hypertension incidence among lean participants, though the association disappeared once baseline blood pressure levels were added to the models. Models investigating change in systolic or diastolic blood pressure levels found higher baseline levels of insulin area under the glucose tolerance curve predicted greater increases in systolic blood pressure in non-Hispanic Whites only.

CONCLUSIONS

Hypertension incidence rates were similar in Hispanics and non-Hispanic Whites. Higher levels of insulin area were associated with larger increases in systolic blood pressure among non-Hispanic Whites only.

Chlamydia trachomatis antibody titers and hysterosalpingography in predicting tubal disease in infertility patients

OBJECTIVE

To determine if the number of diagnostic laparoscopies done on women without tubal adhesive disease could be reduced by testing for tubal disease with Chlamydia trachomatis antibody titers and hysterosalpingography (HSG), either singly or together.

DESIGN

Historical prospective chart review.

SETTING

The Colorado Kaiser Permanente Reproductive Endocrinology Clinic.

PATIENTS

All 703 infertility patients who had C. trachomatis antibody titers done from March 2, 1988 to April 30, 1992. The final study group was comprised of 218 patients who had antibody titers, HSG, and laparoscopy.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Sensitivity, negative predictive value, and false-positive rate were the test characteristics of interest. Tubal disease was identified by laparoscopy.

RESULTS

For HSG testing, the sensitivity was 78% and the negative predictive value was 85%. For C. trachomatis titers, the sensitivity was also 78% and the negative predictive value was 82%. Ninety-five percent confidence intervals for sensitivity and negative predictive value overlapped, indicating that there was no significant difference. However, false-negative rates were the same for the two tests, but false-positive rates were lowest for HSG and series testing.

CONCLUSIONS

To minimize false-positive tests and thus, to minimize unnecessary laparoscopies, HSG testing either alone or combined with the C. trachomatis antibody titer as series tests yielded a significantly lower false-positive rate. In our study group, if both tests were negative, tubal disease was identified on laparoscopy in only 5% of cases. Choice of most cost-effective test sequence will depend on who bears the cost. Further studies of cost-benefit using well-defined testing sequences are needed to determine if C. trachomatis antibody titers in series with HSG would be more cost effective than HSG alone in detecting tubal disease.

Birth size and risk of insulin-dependent diabetes mellitus (IDDM)

A case-control study was conducted to test the hypotheses that birth size is increased in infants who develop IDDM in childhood and that birth size differs by diagnosis age. Cases were non-Hispanic white (NHW) children randomly selected from the Colorado IDDM Registry (n = 221). Controls (n = 197) were NHW children frequency-matched to cases by age-group and gender. Self-administered questionnaires collected birth size and demographic data. There were no significant univariate differences in birth weight (cases 3303.0 g; controls, 3346.1 g; P = 0.40), birth length (cases, 50.8 cm; controls, 51.2 cm; P = 0.28), or ponderal index (cases, 2.52; controls, 2.49; P = 0.92). The case/control odds ratio (OR) controlling for gender, maternal education, and birth place was 1.0 (95% confidence interval (CI) 0.4, 2.5) for the highest category of birth weight compared to the lowest. There were no statistically significant case/control differences in ponderal index (highest to lowest category OR = 1.1; 95% CI 0.6, 2.0) or birth length (1 cm increase OR, 1.0; 95% CI 0.9, 1.2). Similarly, analysis by age-at-diagnosis groups revealed no significant differences, suggesting that birth size does not reveal prenatal diabetogenic influences.