Merrily Poth

Should triglycerides and the triglycerides to high-density lipoprotein cholesterol ratio be used as surrogates for insulin resistance?

The aims of the present study were to examine whether triglycerides (TG) and the triglyceride to high-density lipoprotein cholesterol ratio (TG/HDL-C) could predict insulin resistance in healthy African Americans and whites. This cross-sectional study included 99 African American and 50 white men and women between 18 and 45 years of age with body mass indexes between 18.5 and 38.0 kg/m(2). Anthropometric measures were obtained; and overnight fasting blood was collected for TG, HDL-C, glucose, and insulin. Insulin resistance was defined by fasting insulin concentration of at least 13.13 microU/mL and homeostasis model assessment of insulin resistance (HOMA-IR) of at least 2.5. Receiver operating characteristic curves were used to analyze the data. African Americans and whites had comparable demographic and anthropometric measures. Fasting insulin was higher in African Americans (12.4 +/- 7.8 microU/mL) than whites (10.2 +/- 7.5 microU/mL), but HOMA-IR did not differ significantly (African Americans, 2.9 +/- 2.0; whites, 2.4 +/- 1.9). Triglycerides and TG/HDL-C were significantly lower in African Americans (TG, 68.2 +/- 43.3 mg/dL; TG/HDL-C, 1.8 +/- 2.1) compared with whites (TG, 105.4 +/- 55.2 mg/dL; TG/HDL-C, 2.8 +/- 1.8). Area under the receiver operating characteristic curves revealed that both TG and TG/HDL-C were acceptable markers of insulin resistance, as defined by fasting insulin concentration, in whites, 0.770 and 0.765, respectively, but poor predictors in African Americans, 0.633 and 0.651, respectively. Similarly, TG and TG/HDL-C were acceptable in predicting insulin resistance, as measured by HOMA-IR, in whites, 0.763 and 0.770, respectively, but poor in predicting HOMA-IR in African Americans, with areas of 0.625 and 0.639, respectively. In conclusion, the relationship between TG and TG/HDL-C with insulin resistance differs by ethnicity; and using TG and TG/HDL-C to predict insulin resistance in African Americans would not be appropriate.

Allostatic load and health status of African Americans and whites.

OBJECTIVES To compare health risks in 84 healthy African American and 45 white men and women after calculating allostatic load (AL) from biologic, psychosocial, and behavioral measures. METHODS Participants (18-45 years) ranging in weight from normal to obese and without hypertension or diabetes. Fitness, body fat, CRP, mood, social support, blood pressure, sleep and exercise habits, coping, and insulin responses were dichotomized as low/high risk and summed for AL. RESULTS African Americans (3.4±1.9) had significantly higher AL than that of whites (2.4±1.9; P<0.05). Significantly more African Americans had AL≥3 (67.9%) than did whites (48.9%). CONCLUSIONS Identifying cumulative AL may help identify and address the underpinnings of health disparities in African Americans.

Cardiovascular Fitness and Risk Factors of Healthy African Americans and Caucasians

BACKGROUND African Americans have a higher prevalence of and mortality rates from cardiovascular disease than Caucasians. One important risk factor for cardiovascular disease is poor cardiovascular fitness. We quantified associations between fitness and related primary risk factors for cardiovascular disease in healthy African Americans and Caucasians. METHODS AND RESULTS Participants included African American (n = 91) and Caucasian (n = 51) men and women aged 18 to 45 years with a body mass index less than 38 kg/m2, fasting blood glucose less than 126 mg/dL, and blood pressure less than 140/90 mm Hg. Fitness, waist and hip circumference, percent body fat, fasting blood glucose, insulin, lipid profiles, and C-reactive protein (CRP) were measured. The majority of African Americans (57.1%) were low-fair fitness (Caucasians, 31.4%), and only 20.8% were good/high fitness (Caucasians, 39.2%). The number of cardiovascular disease risk factors increased with decreasing fitness, and CRP was negatively associated with fitness in both groups. CONCLUSIONS Low fitness may characterize apparently healthy African Americans as at risk for cardiovascular disease. Including fitness as a risk factor may improve early identification of at-risk African Americans. Importantly, prescribing exercise as medicine and promoting regular physical activity to improve fitness is essential among African Americans.

Diagnostic Criteria for Metabolic Syndrome: Caucasians Versus African-Americans

BACKGROUND Metabolic syndrome is a constellation of risk factors used to identify individuals at greatest risk for developing cardiovascular disease (CVD). Early diagnosis of CVD would benefit African-Americans (AA), who have a higher prevalence of and mortality rate from CVD compared to Caucasians (CA). Two definitions for metabolic syndrome were used to classify healthy CA and AA, and evaluate how other CVD risk factors [C-reactive protein (CRP), percent body fat, fitness level, insulin resistance, and non-high-density lipoprotein cholesterol (HDL-C)] changed metabolic syndrome classification. METHODS Healthy AA (n = 97) and CA (n = 51) ranging from normal weight to obese, 18-45 years of age, with neither hypertension nor diabetes, were evaluated for cardiorespiratory fitness, height, weight, percent body fat, hip and waist circumference, blood pressure (BP), and fasting blood glucose, insulin, triglycerides, HDL, non-HDL-C, and CRP. Participants were classified as meeting the criteria for metabolic syndrome according to the National Cholesterol Education Program Adult Treatment Panel III 2004 (NCEP ATP III) and the International Diabetes Federation (IDF) definitions. RESULTS Significant ethnic differences (P < 0.01) in classification were noted for both metabolic syndrome definitions (NCEP ATP III, CA = 16.7% vs. AA = 5.7%; IDF, CA = 23.5% vs. AA = 8.2%). Ethnic differences were eliminated when fitness level or percent body fat was included as a criterion. CONCLUSIONS If diagnosis of metabolic syndrome is intended for early recognition of CVD risk and slowing CVD development, current definitions for metabolic syndrome will not capture healthy AA. Health-care providers may consider assessing percent body fat and participation in regular exercise, because these criteria would help identify AA at risk.

Role of plasma adiponectin /C-reactive protein ratio in obesity and type 2 diabetes among African Americans

BACKGROUND Obesity is a modifiable risk factor for hypertension and T2D. Objective(s): We examined relations between fasting plasma adiponectin (ADIP), C-reactive protein (CRP) concentrations and markers of T2D in African Americans (AA). METHODS Fasting plasma ADIP, CRP, Insulin (IN), HOMA-IR, lipid profiles, body fat percent (%BF), waist circumference (WC), body mass index (BMI) and blood pressure measures were determined in AA women (W: n=77) and men (M: n=34). Participants were classified into: 1) Normal fasting glucose (FG) and Normal %BF; 2) Normal FG and High %BF; and 3) High FG. RESULTS Compared to men, women had significantly higher mean ADIP (W: 31.4±2.9 vs. M: 18.0±4.4 ng/L), CRP (W: 3.2±0.3 vs. M: 2.0±0.5 mg/L), %BF (W: 41.2±0.9 vs. M: 27.2±1.3), and BMI (W: 32.3±0.7 vs. M: 29.2±1.1 kg/m2). Women with normal FG and %BF had significantly higher ADIP (64.0±6.0) and lower CRP (1.3±0.6) concentrations than normal FG/ high %BF (ADIP: 37.0±5.0 and CRP: 3.1 ±0.5) and high FG (ADIP: 15.1±4.1 and CRP: 4.0 ± 0.5) groups. Women with high ADIP to CRP ratio had favorable metabolic and anthropometric profiles. CONCLUSION Low ADIP and high CRP are associated with excessive %BF and FG in AA women. ADIP/CRP, may be useful for detecting metabolic dysregulation.

Plasma Proteomic Signature in Overweight Girls Closely Correlates with Homeostasis Model Assessment (HOMA), an Objective Measure of Insulin Resistance.

Obesity is known to be associated with a large number of long-term morbidities, and while in some cases the relationship of obesity and the consequences is clear (for example, excess weight and lower extremity orthopedic problems) in others the mechanism is not as clear. One common system of categorizing overweight in terms of the likelihood of negative consequences involves using the concept of “metabolic syndrome”. We hypothesized that the development of a plasma protein profile of overweight adolescents with and without the metabolic syndrome might give a more precise and informative picture of the disease process than the current clinical categorization and permit early targeted intervention. For this paper, we used antibody microarrays to analyze the plasma proteome of a group of 15 overweight female adolescent patients. Upon analysis of the proteome, the overweight patients diverged from the nonoverweight female controls. Furthermore, the overweight patients were divided by the analysis into two population clusters, each with distinctive protein expression patterns. Interestingly, the clusters were characterized by differences in insulin resistance, as measured by HOMA. Categorization according to the presence or absence of the metabolic syndrome did not yield such clusters.