Disparities in insulin resistance between black and white adults in the United States: The role of lifespan stress exposure.

BACKGROUND: Disparities in insulin resistance between Black and White adults in the United States are well documented, yet relatively little is known about the psychosocial or biological antecedents of these inequities. The current study examined childhood adversity and contemporaneous psychosocial stressors in adulthood as possible mediators of the racial disparity in insulin resistance. Inflammatory and hypothalamic-pituitary adrenal (HPA) axis mechanisms implicated in associations between lifespan stress exposure and insulin resistance were also considered. METHODS: Data were derived from the biomarker component of the Midlife in the United States Study (N = 1170, 20% Black, 56% female, Mean age = 54.7 years, SD = 11.6). A homeostatic model assessment of insulin resistance (HOMA-IR) was calculated from fasting glucose and insulin concentrations. Twelve risk factors relating to household dysfunction, socioeconomic disadvantage, and maltreatment were sum scored to index childhood adversity. Measures of adult stress included socioeconomic adversity, major stressful events, everyday discrimination, and lifetime discrimination. RESULTS: Levels of insulin resistance were higher among Black than White adults. Childhood adversity was positively associated with HOMA-IR, and attenuated 18% of the race difference. Measures of adult stress mediated 33% of the association between childhood adversity and HOMA-IR, and accounted for an additional 47% of the race difference. Higher inflammation and lower nocturnal cortisol both played an important role in mediating the association between stress exposure and HOMA-IR. CONCLUSIONS: Findings are consistent with prior research showing that childhood adversity and adult stress are salient predictors of glucose metabolism, and extend this work by showing that lifespan stress exposures attenuate a significant portion of the Black-White disparity in HOMA-IR. Results also suggest stress effects on insulin resistance through inflammatory and HPA-axis pathways.

Gender differences in the pathways from childhood disadvantage to metabolic syndrome in adulthood: An examination of health lifestyles.

We investigate whether socioeconomic status (SES) in childhood shapes adult health lifestyles in domains of physical activity (leisure, work, chores) and diet (servings of healthy [i.e., nutrient-dense] vs. unhealthy [energy-dense] foods). Physical activity and food choices vary by gender and are key factors in the development of metabolic syndrome (MetS). Thus, we examined gender differences in the intervening role of these behaviors in linking early-life SES and MetS in adulthood. We used survey data (n = 1054) from two waves of the Midlife in the U.S. Study (MIDUS 1 and 2) and biomarker data collected at MIDUS 2. Results show that individuals who were disadvantaged in early life are more likely to participate in physical activity related to work or chores, but less likely to participate in leisure-time physical activity, the domain most consistently linked with health benefits. Women from low SES families were exceedingly less likely to complete recommended amounts of physical activity through leisure. Men from low SES consumed more servings of unhealthy foods and fewer servings of healthy foods. The observed associations between childhood SES and health lifestyles in adulthood persist even after controlling for adult SES. For men, lack of leisure-time physical activity and unhealthy food consumption largely explained the association between early-life disadvantage and MetS. For women, leisure-time physical activity partially accounted for the association, with the direct effect of childhood SES remaining significant. Evidence that material deprivation in early life compromises metabolic health in adulthood calls for policy attention to improve economic conditions for disadvantaged families with young children where behavioral pathways (including gender differences therein) may be shaped. The findings also underscore the need to develop gender-specific interventions in adulthood.

Childhood Socioeconomic Disadvantage, Occupational, Leisure-Time, and Household Physical Activity, and Diabetes in Adulthood.

BACKGROUND: Regular physical activity is a key way to prevent disease. However, we have a limited understanding of the socioeconomic precursors and glucoregulatory sequelae of engaging in physical activity in different domains. METHODS: We examined the associations among life course socioeconomic disadvantage; meeting the physical activity guidelines with leisure-time physical activity, occupational physical activity, or household physical activity; and prediabetes and diabetes in the Midlife in the United States national study (N = 986). RESULTS: Childhood disadvantage was associated with lower odds of meeting the guidelines with leisure-time physical activity (odds ratio = 0.75; 95% confidence interval, 0.65-0.86). Adulthood disadvantage was associated with higher odds of meeting the guidelines with occupational physical activity (odds ratio = 1.94; 95% confidence interval, 1.49-2.53). Importantly, while meeting the guidelines with leisure-time physical activity was associated with lower odds of prediabetes and diabetes, we found no evidence for associations among occupational physical activity, household physical activity, and glucoregulation. CONCLUSION: Current US physical activity guidelines do not differentiate between physical activity for leisure or work, assuming that physical activity in any domain confers comparable health benefits. We documented important differences in the associations among lifetime socioeconomic disadvantage, physical activity domain, and diabetes, suggesting that physical activity domain potentially belongs in the guidelines, similar to other characteristics of activity (eg, type, intensity).

Psychological resources and glucoregulation in Japanese adults: Findings from MIDJA.

OBJECTIVE: To examine associations between glucoregulation and 3 categories of psychological resources: hedonic well-being (i.e., life satisfaction, positive affect), eudaimonic well-being (i.e., personal growth, purpose in life, ikigai), and interdependent well-being (i.e., gratitude, peaceful disengagement, adjustment) among Japanese adults. The question is important given increases in rates of type 2 diabetes in Japan in recent years, combined with the fact that most prior studies linking psychological resources to better physical health have utilized Western samples. METHOD: Data came from the Midlife in Japan Study involving randomly selected participants from the Tokyo metropolitan area, a subsample of whom completed biological data collection (N = 382; 56.0% female; M(SD)age = 55.5(14.0) years). Glycosylated hemoglobin (HbA1c) was the outcome. Models adjusted for age, gender, educational attainment, smoking, alcohol, chronic conditions, body mass index (BMI), use of antidiabetic medication, and negative affect. RESULTS: Purpose in life (ß = -.104, p = .021) was associated with lower HbA1c, and peaceful disengagement (ß = .129, p = .003) was associated with higher HbA1c in fully adjusted models. Comparable to the effects of BMI, a 1 standard deviation change in well-being was associated with a .1% change in HbA1c. CONCLUSIONS: Associations among psychological resources and glucoregulation were mixed. Healthy glucoregulation was evident among Japanese adults with higher levels of purpose in life and lower levels of peaceful disengagement, thereby extending prior research from the United States. The results emphasize the need for considering sociocultural contexts in which psychological resources are experienced in order to understand linkages to physical health. (PsycINFO Database Record

Leisure-time, occupational, household physical activity and insulin resistance (HOMAIR) in the Midlife in the United States (MIDUS) national study of adults.

Physical activity is a critical cornerstone of successful diabetes prevention and management. Current U.S. physical activity guidelines do not differentiate among physical activity for leisure, work, or other purposes, effectively implying that physical activity in any domain confers the same health benefits. It is currently unknown whether physical activity performed in different domains (leisure-time physical activity = LTPA, occupational physical activity = OPA, and household physical activity = HPA) is associated with insulin resistance. The associations between LTPA, OPA, HPA, and insulin resistance (indexed by homeostatic model assessment of insulin resistance = HOMAIR) were determined in the MIDUS (Midlife in the U.S.; 1995-2006) national study (N = 1229, ages 34-84). Not meeting physical activity guidelines with LTPA was associated with a 34% higher HOMAIR among participants with diabetes, 42% higher HOMAIR among participants with prediabetes, and 17% higher HOMAIR among participants with normal glucoregulation. These associations were slightly attenuated but remained significant after further adjusting for obesity status, education, smoking, and alcohol intake. There was no evidence that engaging in OPA or HPA was significantly associated with HOMAIR. These results confirm the health-promoting role of LTPA and suggest that LTPA may provide unique glucoregulatory benefits, as opposed to HPA and OPA. Physical activity domain is an important dimension that potentially belongs in the guidelines, similarly to intensity, frequency, duration, and type.

Depression Amplifies the Influence of Central Obesity on 10-Year Incidence of Diabetes: Findings from MIDUS.

BACKGROUND: Central obesity is a major risk factor for diabetes but many obese individuals never develop diabetes, suggesting the presence of important effect modifiers. Depression has emerged as a key risk factor for poor glycemic control, but to our knowledge, no previous work has investigated whether depression amplifies the effect of central obesity on glucoregulation. METHODS AND FINDINGS: We used a national sample of adults without prevalent diabetes (MIDUS; N = 919) to test for synergy between central obesity and depression in the development of diabetes 10 years later. We found that depression amplified the association of waist-to-hip ratio (WHR) with incident diabetes adjusted for age, race, gender, education, physical activity, and sleep problems (p = 0.01 for test of interaction). The relative risk for incident diabetes per every 0.1 increment in WHR was 1.75 (95% CI: 1.31; 2.33) in those without depression and 3.78 in those with depression (95% CI: 2.14; 6.66). CONCLUSIONS: These results confirm the role of depression as a robust risk factor for the development of diabetes and for the first time, demonstrate a synergy between depression and central obesity. Identifying and addressing depression could prove to be an effective approach to preventing diabetes in at risk individuals. Ultimately, elucidating the interplay among risk factors from different domains will be key to understanding multifactorial diseases such as diabetes and informing theory-based, patient-centered interventions aimed at reducing diabetes risk.

Parental History of Diabetes, Positive Affect, and Diabetes Risk in Adults: Findings from MIDUS.

BACKGROUND: Family history of diabetes is one of the major risk factors for diabetes, but significant variability in this association remains unexplained, suggesting the presence of important effect modifiers. PURPOSE: To our knowledge, no previous work has examined whether psychological factors moderate the degree to which family history of diabetes increases diabetes risk. METHODS: We investigated the relationships among parental history of diabetes, affective states (positive affect, negative affect, and depressed affect), and diabetes in 978 adults from the MIDUS 2 national sample. RESULTS: As expected, parental history of diabetes was associated with an almost threefold increase in diabetes risk. We found a significant interaction between positive affect and parental history of diabetes on diabetes (p = .009): higher positive affect was associated with a statistically significant lower relative risk for diabetes in participants who reported having a parental history of diabetes (RR = .66 per unit increase in positive affect; 95 % CI = .47; .93), but it did not influence diabetes risk for participants who reported no parental history of diabetes (p = .34). This pattern persisted after adjusting for an extensive set of health and sociodemographic covariates and was independent of negative and depressed affect. CONCLUSIONS: These results suggest that psychological well-being may protect individuals at increased risk from developing diabetes. Understanding such interactions between non-modifiable risk factors and modifiable psychological resources is important for delineating biopsychosocial pathways to diabetes and informing theory-based, patient-centered interventions to prevent the development of diabetes.

Anger, adiposity, and glucose control in nondiabetic adults: findings from MIDUS II.

Anger has been linked to cardiovascular disease, but few studies have examined the relationship between anger and type 2 diabetes. The aim was to investigate associations among different indicators of anger expression, adiposity, and nondiabetic glucose metabolism in a national survey of adults. Participants were 939 adults without diabetes in the Midlife in the US study (MIDUS II). Glucose metabolism was characterized by fasting glucose, insulin, insulin resistance, and glycosylated hemoglobin (HbA1c). Spielberger's Anger Expression inventory was used to measure suppressed anger (anger-in), expressed anger (anger-out), and controlled anger (anger-control). We investigated the relationship between anger and glucose metabolism, and whether anger amplified the adverse relationship between body weight distribution (body mass index = BMI and waist-to-hip ratio = WHR) and glucose metabolism. Multivariate-adjusted analyses revealed an association between anger-out and both insulin and insulin resistance. As predicted, anger-in amplified the relationships between BMI and insulin and insulin resistance, while anger-out amplified the association between WHR and insulin and insulin resistance. Low anger-control was associated with higher glucose. None of the three anger measures was significantly associated with HbA1c. Our findings extend previous research on anger as a potential risk factor for type 2 diabetes by demonstrating that anger expression is associated with clinical indicators of glycemic control, especially among those with pre-existing risk due to obesity and high central adiposity.

Perceived weight discrimination amplifies the link between central adiposity and nondiabetic glycemic control (HbA1c).

BACKGROUND: While the preclinical development of type 2 diabetes is partly explained by obesity and central adiposity, psychosocial research has shown that chronic stressors such as discrimination have health consequences as well. PURPOSE: We investigated the extent to which the well-established effects of obesity and central adiposity on nondiabetic glycemic control (indexed by HbA(1c)) were moderated by a targeted psychosocial stressor linked to weight: perceived weight discrimination. METHODS: The data came from the nondiabetic subsample (n = 938) of the Midlife in the United States (MIDUS II) survey. RESULTS: Body mass index (BMI), waist-to-hip ratio, and waist circumference were linked to significantly higher HbA(1c) (p < 0.001). Multivariate-adjusted models showed that weight discrimination exacerbated the effects of waist-to-hip ratio on HbA(1c) ( p < 0.05), such that people who had higher waist-to-hip ratios and reported weight discrimination had the highest HbA(1c) levels. CONCLUSION: Understanding how biological and psychosocial factors interact at nondiabetic levels to increase vulnerability could have important implications for public health and education strategies. Effective strategies may include targeting sources of discrimination rather than solely targeting the health behaviors and practices of overweight and obese persons.

Coping and positive affect predict longitudinal change in glycosylated hemoglobin.

OBJECTIVE: This study investigated whether different psychosocial factors predicted levels of glycosylated hemoglobin (HbA1c) over time, after adjusting for covariates and baseline level of HbA1c. DESIGN: These questions were investigated with a longitudinal sample (N = 97, age = 61-91) of older women without diabetes. HbA1c levels and psychosocial measures were obtained at baseline and 2-year follow-up. MAIN OUTCOME MEASURES: Coping strategies, positive affect, medical history, and health behaviors were assessed using self-administered questionnaires. HbA1c were obtained during the respondents' overnight stay at the General Clinical Research Center (GCRC) at the University of Wisconsin-Madison. RESULTS AND CONCLUSION: Regression analyses showed that higher levels of problem-focused coping, venting, and positive affect predicted lower levels of HbA1c, after controlling for baseline HbA1c and sociodemographic and health factors. Furthermore, positive affect was found to moderate the effects of problemfocused coping (active, instrumental social support, suppressing competing activities). The pattern of interaction showed that the adverse effects of low problem-focused coping on cross-time changes in HbA1c were amplified among those who also had low levels of positive affect.

Socioeconomic status and psychological well-being predict cross-time change in glycosylated hemoglobin in older women without diabetes.

OBJECTIVE: To investigate whether socioeconomic status and psychological well-being (eudaimonic and hedonic aspects) predicted nondiabetic levels of glycosylated hemoglobin (HbA1c) over time, after adjusting for covariates and baseline level of HbA1c. METHODS: These questions were investigated with a longitudinal sample (n = 97; age = 61-91 years) of older women without diabetes. Socioeconomic status, well-being, and health behaviors were assessed using self-administered questionnaires. Fasting blood samples for assays of HbA1c were obtained before 7 AM during the respondents' overnight stay at the General Clinical Research Center at the University of Wisconsin-Madison. All measurements were obtained at baseline and 2-year follow-up. RESULTS: Regression analyses showed that higher income and positive affect predicted lower levels of HbA1c, after controlling for baseline HbA1c and health factors. Additionally, three well-being measures (purpose in life, personal growth, and positive affect) moderated the relationship between income and HbA1c. CONCLUSION: These results suggest that psychological well-being and socioeconomic status interact in important ways in influencing nondiabetic glucose metabolism.