Animal models provide insight into psychosomatic factors in diabetes

Prevalence and characteristics of prediabetes in workers in industry

AIM

To examine the prevalence of work stress and prediabetes in computer technology company employees; to analyse the relationships among stress, work stress, and prediabetes; and to explore the potential mediating effects sleep on the relationship between work stress and prediabetes.

DESIGN

A descriptive, cross-sectional design was used. A convenience sample included employees from a large computer technology company in central Texas.

METHODS

Data collection during March-October 2015 included: retrospective electronic medical record review and online surveys. Electronic medical record review data included: height, weight, waist circumference, blood pressure, high-density lipids, triglycerides, and fasting glucose. Online surveys collected demographic, global stress, diet, exercise, coping, sleep and work stress data from participants. Spearman rho calculations analyzed associations between demographic, socio-cultural factors, health behaviours, work stress, and prediabetes variables. Logistic regression analyses identified probability variables. A structural equation model examined mediating variables.

RESULTS

Prediabetes prevalence was lower and prevalence of work stress was higher in the participant sample than in the USA population. Findings suggested that low job imbalance increases the probability for prediabetes. Job imbalance was inversely related to prediabetes. Three variables increased the probability prediabetes: alcohol, job imbalance, and sleep. Sleep potentially modified the relationship between job imbalance and prediabetes. Participants were college-educated males working in white-collar, technical jobs. Participants had high rates of work stress. Job imbalance was inversely related to prediabetes, which challenges previous empirical data. Future research should continue to explore the relationship between work stress and prediabetes in this population.

CONCLUSIONS

This study explored the relationship between work stress and prediabetes in a white-collar worker population in technical industry. Findings suggested that workers in industry have a unique type of stress. Nurses who learn to recognize the non-traditional risk factors for prediabetes can improve screening for prediabetes by including work stress and poor sleep questions.

Plasma epinephrine predicts fasting glucose in centrally obese African-American women

The high prevalence of diabetes in African-American (AA) women has been widely assumed to be related to the greater prevalence of obesity in this group. Catecholamine release acting on central adipose tissue has been proposed to be a contributing factor. The aim of this article was to examine the interaction of plasma catecholamines and central adiposity on fasting and nonfasting glucose levels in two separate samples. In both studies, the women were healthy, nondiabetic of similar age. In addition, both studies assessed plasma epinephrine (EPI) and norepinephrine (NOREPI) levels collected at three time points. In study 1, catecholamines were measured during a standardized laboratory mental stress task and in study 2, they were measured during the initial phase (10 min) of an intravenous glucose tolerance test (IVGTT). Results from both studies revealed significant effects of EPI on fasting glucose in the obese women. In study 1, mean EPI levels were significantly related to fasting glucose in AA women with high trunk fat (beta = 0.60, P < 0.001). Because high BMI was associated with high trunk fat in women, we used BMI >30 as a proxy for high trunk fat (>32%) in study 2. In study 2, EPI response to the glucose bolus was a strong predictor of fasting glucose in AA women with BMI >30 (beta = 0.75, P < 0.003). We conclude that the effect of central adiposity on fasting glucose may be moderated by plasma EPI. This suggests that adrenal medullary activity could play a role in the pathophysiology of type 2 diabetes.

Old World Nonhuman Primate Models of Type 2 Diabetes Mellitus

Type 2 diabetes mellitus is a major health problem of increasing incidence. To better study the pathogenesis and potential therapeutic agents for this disease, appropriate animal models are needed. Old World nonhuman primates (NHPs) are a useful animal model of type 2 diabetes; like humans, the disease is most common in older, obese animals. Before developing overt diabetes, NHPs have a period of obesity-associated insulin resistance that is initially met with compensatory insulin secretion. When either a relative or absolute deficiency in pancreatic insulin production occurs, fasting glucose concentrations begin to increase and diabetic signs become apparent. Pathological changes in pancreatic islets are also similar to those seen in human diabetics. Initially there is hyperplasia of the islets with abundant insulin production typically followed by replacement of islets with islet-associated amyloid. Diabetic NHPs have detrimental changes in plasma lipid and lipoprotein concentrations, lipoprotein composition, and glycation, which may contribute to progression of atherosclerosis. As both the prediabetic condition (similar to metabolic syndrome in humans) and overt diabetes become better defined in monkeys, their use in pharmacological studies is increasing. Likely due to their genetic similarity to humans and the similar characteristics of the disease in NHPs, NHPs have been used to study recently developed agonists of the peroxisome proliferators-activated receptors. Importantly, agonists of the different receptor subclasses elicit similar responses in both humans and NHPs. Thus, Old World NHPs are a valuable animal model of type 2 diabetes to study disease progression, associated risk factors, and potential new treatments.

Socioeconomic status and diagnosed diabetes incidence

AIMS

To investigate the association between socioeconomic status (SES) and incidence of diabetes.

METHODS

We investigated three measures of SES and incidence of diagnosed diabetes among women and men in the NHANES I Epidemiologic Followup Study, 1971-1992, who were free of diagnosed diabetes in 1980.

RESULTS

Among women, diabetes incidence was inversely associated with income (measured as percent of the poverty level), education, and occupational status, adjusting for age and race/ethnicity. The hazard ratio (HR) for women with > 16 years education was 0.26 (95% confidence interval (CI) 0.13-0.54) relative to those with < 9 years of education. Adjustment for potential mediators, including body size variables, diet, physical activity, and alcohol and tobacco use, substantially attenuated the associations with income and education. Among men a trend toward lower diabetes incidence with higher income and higher education was evident (the HR for men with household income > 5 times the poverty level was 0.44 (95% CI 0.19-0.98) relative to those under the poverty line), but there was no inverse association of diabetes incidence with occupational status.

CONCLUSIONS

SES, assessed with any of three common measures, is a risk factor for diagnosed diabetes in women. Among men these associations are less consistent.

Diabetes induces metabolic adaptations in rat liver mitochondria: role of coenzyme Q and cardiolipin contents

Several studies have been carried out to evaluate the alterations in mitochondrial functions of diabetic rats. However, results are sometimes controversial, since experimental conditions diverge, including age and strain of used animals. The purpose of this study was to evaluate the metabolic modifications in liver mitochondria, both in the presence of severe (STZ-treated rats) and mild hyperglycaemia [Goto-Kakizaki (GK) rats], when compared with control animals of similar age. Moreover, metabolic alterations were evaluated also at initial and advanced stages of the disease. We observed that both models of diabetes (type 1 and type 2) presented a decreased susceptibility of liver mitochondria to the induction of permeability transition (MPT). Apparently, there is a positive correlation between the severity of diabetes mellitus (and duration of the disease) and the decline in the susceptibility to MPT induction. We also found that liver mitochondria isolated from diabetic rats presented some metabolic adaptations, such as an increase in coenzyme Q and cardiolipin contents, that can be responsible for the observed decrease in the susceptibility to multiprotein pore (MPTP) opening.

Effect of acute psychotic stress in nondiabetic subjects on beta-cell function and insulin sensitivity

OBJECTIVE

To determine the effect of acute psychotic stress on glucose homeostasis in nondiabetic subjects.

RESEARCH DESIGN AND METHODS

Beta-cell function and insulin sensitivity were determined by the homeostasis model assessment in 39 nondiabetic patients with acute psychotic stress reaction admitted to a psychiatric ward. The clinical global impression (CGI) score was used to evaluate the level of psychological stress. Patients were assessed on admission, after 2 weeks, before discharge, and 6 months after discharge.

RESULTS

The mean CGI score decreased significantly with time: 5.3 +/- 0.8 and 1.6 +/- 0.7 on admission and predischarge, respectively (P < 0.001). This was associated with a significant reciprocal increase of mean beta-cell function from 96.8 +/- 33.2 to 134.4 +/- 60% at admission and postdischarge, respectively (P < 0.003), and a decrease of mean insulin sensitivity from 101.7 +/- 36 to 77.1 +/- 34.8% (P < 0.001). In contrast, mean glucose and HbA(1c) levels did not change significantly. Subgroup analysis demonstrated that patients with the highest stress score on admission (> or =6) had significantly higher glucose (P = 0.01) and insulin levels (P = 0.04) than patients with lower score (<6). Furthermore, insulin sensitivity and CGI score on admission were inversely correlated (r = -0.38, P < 0.02). In these patients, no correlation was found between beta-cell function or insulin sensitivity and BMI.

CONCLUSIONS

These data indicate that beta-cell function and insulin sensitivity are inversely correlated with acute psychotic stress.

Prevalence of anxiety in adults with diabetes: a systematic review

BACKGROUND

Anxiety is associated with decreased functioning and quality of life. It may have added importance in diabetes for its potential adverse effects on regimen adherence and glycemic control.

OBJECTIVE

To estimate the prevalence of clinically significant anxiety in adults with diabetes.

RESEARCH DESIGN AND METHODS

MEDLINE and PsycINFO databases and published reference lists were searched to identify studies that determined the prevalence of anxiety in diabetes from threshold scores on self-report measures or from diagnostic interviews. Prevalence was calculated as an aggregate mean weighted by the combined number of subjects in the included studies.

RESULTS

Eighteen studies having a combined population (N) of 4076 (2584 diabetic subjects, 1492 controls) satisfied the inclusion criteria. Most did not adjust for the effects of moderator variables such as gender, and only one was community-based. Generalized anxiety disorder (GAD) was present in 14% of patients with diabetes. The subsyndromal presentation of anxiety disorder not otherwise specified and of elevated anxiety symptoms were found in 27% and 40%, respectively, of patients with diabetes. The prevalence of elevated symptoms was significantly higher in women compared to men (55.3% vs. 32.9%, P<.0001) and similar in patients with Type 1 vs. Type 2 diabetes (41.3% vs. 42.2%, P=.80).

CONCLUSION

GAD is present in 14% and elevated symptoms of anxiety in 40% of patients with diabetes who participate in clinical studies. Additional epidemiological studies are needed to determine the prevalence of anxiety in the broader population of persons with diabetes.

Aging is a deprivation syndrome driven by a germ-soma conflict

Evolution through natural selection can be described as driven by a perpetual conflict of individuals competing for limited resources. Recently, I postulated that the shortage of resources godfathered the evolutionary achievements of the differentiation-apoptosis programming [Rev. Neurosci. 12 (2001) 217]. Unicellular deprivation-induced differentiation into germ cell-like spores can be regarded as the archaic reproduction events which were fueled by the remains of the fratricided cells of the apoptotic fruiting body. Evidence has been accumulated suggesting that conserved through the ages as the evolutionary legacy of the germ-soma conflict, the somatic loss of immortality during the ontogenetic segregation of primordial germ cells recapitulates the archaic fate of the fruiting body. In this heritage, somatic death is a germ cell-triggered event and has been established as evolutionary-fixed default state following asymmetric reproduction in a world of finite resources. Aging, on the other hand, is the stress resistance-dependent phenotype of the somatic resilience that counteracts the germ cell-inflicted death pathway. Thus, aging is a survival response and, in contrast to current beliefs, is antagonistically linked to death that is not imposed by group selection but enforced upon the soma by the selfish genes of the "enemy within". Environmental conditions shape the trade-off solutions as compromise between the conflicting germ-soma interests. Mechanistically, the neuroendocrine system, particularly those components that control energy balance, reproduction and stress responses, orchestrate these events. The reproductive phase is a self-limited process that moulds onset and progress of senescence with germ cell-dependent factors, e.g. gonadal hormones. These degenerate the regulatory pacemakers of the pineal-hypothalamic-pituitary network and its peripheral, e.g. thymic, gonadal and adrenal targets thereby eroding the trophic milieu. The ensuing cellular metabolic stress engenders adaptive adjustments of the glucose-fatty acid cycle, responses that are adequate and thus fitness-boosting under fuel shortage (e.g. during caloric restriction) but become detrimental under fuel abundance. In a Janus-faced capacity, the cellular stress response apparatus expresses both tolerogenic and mutagenic features of the social and asocial deprivation responses [Rev. Neurosci. 12 (2001) 217]. Mediated by the derangement of the energy-Ca(2+)-redox homeostatic triangle, a mosaic of dedifferentiation/apoptosis and mutagenic responses actuates the gradual exhaustion of functional reserves and eventually results in a multitude of aging-related diseases. This scenario reconciles programmed and stochastic features of aging and resolves the major inconsistencies of current theories by linking ultimate and proximate causes of aging. Reproduction, differentiation, apoptosis, stress response and metabolism are merged into a coherent regulatory network that stages aging as a naturally selected, germ cell-triggered and reproductive phase-modulated deprivation response.

Diabetes, diversity, and disparity: what do we do with the evidence?

The US Department of Health and Human Services has developed an initiative called "Eliminating Racial and Ethnic Disparities in Health," which parallels Healthy People 2010, the nation's health goals for the next decade. The initiative focuses on areas of health disparity that are known to affect racially and ethnically diverse groups of the population yet hold the promise of improvement. The first step to addressing such health inequities is to understand the scope and nature of the diseases that contribute to such disparities. This commentary reviews the epidemiology and consequences of type 2 diabetes, particularly as it is manifested in socially and culturally diverse groups, and offers recommendations for actions to address the disparities resulting from diabetes.

Stress hormone-related psychopathology: pathophysiological and treatment implications

Stress is commonly associated with a variety of psychiatric conditions, including major depression, and with chronic medical conditions, including diabetes and insulin resistance. Whether stress causes these conditions is uncertain, but plausible mechanisms exist by which such effects might occur. To the extent stress-induced hormonal alterations (e.g., chronically elevated cortisol levels and lowered dehydroepiandrosterone [DHEA] levels) contribute to psychiatric and medical disease states, manipulations that normalize these hormonal aberrations should prove therapeutic. In this review, we discuss mechanisms by which hormonal imbalance (discussed in the frameworks of "allostatic load" and "anabolic balance") might contribute to illness. We then review certain clinical manifestations of such hormonal imbalances and discuss pharmacological and behavioural treatment strategies aimed at normalizing hormonal output and lessening psychiatric and physical pathology.

Socioeconomic status and type 2 diabetes in African American and non-Hispanic white women and men: evidence from the Third National Health and Nutrition Examination Survey

OBJECTIVES

This study examined the associations of poverty income ratio (PIR), education, and occupational status with type 2 diabetes prevalence among African American and non-Hispanic White (White) women and men aged 40 to 74 years.

METHODS

We analyzed cross-sectional data from the Third National Health and Nutrition Examination Survey, controlling for age and examination-related variables.

RESULTS

Among African American women, there was a strong, graded association between PIR and diabetes, which remained significant after other risk factors were adjusted for. All 3 variables were significantly associated with diabetes among White women. Among White men, only PIR was significantly associated with diabetes. Controlling for risk factors substantially attenuated these associations among White women. There were no significant associations for African American men.

CONCLUSIONS

Socioeconomic status is associated with type 2 diabetes prevalence among women, but not consistently among men. Diabetes prevalence is more strongly associated with PIR than with education or occupational status. These associations are largely independent of other risk factors, especially among African American women. Economic resources should be addressed in efforts to explain and reverse the increasing prevalence of diabetes in the United States.

Glycated hemoglobin as an indicator of social environmental stress among indigenous versus westernized populations

BACKGROUND

This study assessed whether glycated hemoglobin concentration, an indicator of psychogenic stress, differs between indigenous populations and non-indigenous reference groups.

METHODS

Multivariate and stratified analyses were undertaken of cross-sectional data from multi-center community-based diabetes diagnostic and risk factor screening initiatives in Canada and Australia. Population groups were Australian Aborigines (n = 116), Torres Strait Islanders (n = 156), Native Canadians (n = 155), Greek migrants to Australia (n = 117), and Caucasian Australians (n = 67). Measurements included fasting glycated hemoglobin (HbA(1c)) concentration, fasting and 2-h post-load glucose concentrations, body mass index, waist-to-hip ratio, and demographic variables.

RESULTS

Mean HbA(1c) concentrations were greater for indigenous groups than for Greek migrants and Caucasian Australians (P < 0. 0001). The covariate adjusted indigenous versus non-indigenous difference (95% CI) was 0.90 (0.58-1.22) percentage units, 18.2% higher for indigenous people. Stratified analyses indicated greater HbA(1c) for indigenous than for non-indigenous persons with normoglycemia (P = 0.009), impaired glucose tolerance (P = 0.097), and diabetes (P < 0.0001).

CONCLUSIONS

HbA(1c) concentrations are greater for indigenous than for non-indigenous groups. Social changes, low control, and living conditions associated with westernization may be inherently stressful at the biological level for indigenous populations in westernized countries.

Differential effects of restraint stress on hippocampal 5-HT metabolism and extracellular levels of 5-HT in streptozotocin-diabetic rats

Streptozotocin (STZ)-elicited diabetes reduces central serotonin (5-hydroxytryptamine, 5-HT) synthesis/metabolism, but whether this reduction leads to decreased release of 5-HT has only scarcely been investigated. We have thus analysed the impact of STZ diabetes on hippocampal extracellular 5-HT levels both under basal conditions and during restraint stress, a procedure known to stimulate hippocampal 5-HT synthesis/metabolism and release. The pretreatment with STZ (3 weeks beforehand) and the 1 h restraint session respectively decreased and increased hippocampal 5-HT metabolism, as assessed by tissue analysis of 5-HT and 5-hydroxyindoleacetic acid. On the other hand, hippocampal microdialysis revealed no difference in basal levels of extracellular 5-HT levels in (conscious) vehicle- and STZ-pretreated rats, but a differential effect of restraint. Thus, extracellular 5-HT levels increased throughout restraint (maximal increase: 194%) in vehicle-, but not in STZ-pretreated rats. In the latter rat group, plasma corticosterone levels were, however, increased, thus indicating a significant aversiveness to stress. Lastly, because anxiety-related behaviours may be affected by hippocampal serotonergic systems, resting and restrained vehicle- and STZ-pretreated rats were compared (immediately after stress) in an elevated plus-maze of anxiety. Pretreatment with STZ reduced the percent number of open arm entries and the number of closed arm entries, indicating increased anxiety and reduced locomotor activity, respectively. Restraint tended to increase anxiety-related behaviours in all rats, but this trend never reached significance. Our results confirm that gross analyses of 5-HT metabolism do not yield information on 5-HT release, and suggest that the prevalence of diabetes among patients suffering affective disorders could be related to the lack of hippocampal serotonergic response to aversive stimuli.