Two new studies have linked diabetes to socioeconomic status and to depression. Both are linked, socioeconomic status directly and depression indirectly (supported by research Charles Raison and others), to inflammation. Chronic inflammation is known to aggravate diabetes as well as lead to development of the disease.
Both of these articles show that lifestyle and quality of life have a powerful impact on our health.
Association of Lifecourse Socioeconomic Status with Chronic Inflammation and Type 2 Diabetes Risk: The Whitehall II Prospective Cohort Study
Silvia Stringhini, G. David Batty, Pascal Bovet, Martin J. Shipley, Michael G. Marmot, Meena Kumari, Adam G. Tabak, Mika Kivimäki
Socioeconomic adversity in early life has been hypothesized to “program” a vulnerable phenotype with exaggerated inflammatory responses, so increasing the risk of developing type 2 diabetes in adulthood. The aim of this study is to test this hypothesis by assessing the extent to which the association between lifecourse socioeconomic status and type 2 diabetes incidence is explained by chronic inflammation.
Methods and Findings
We use data from the British Whitehall II study, a prospective occupational cohort of adults established in 1985. The inflammatory markers C-reactive protein and interleukin-6 were measured repeatedly and type 2 diabetes incidence (new cases) was monitored over an 18-year follow-up (from 1991–1993 until 2007–2009). Our analytical sample consisted of 6,387 non-diabetic participants (1,818 women), of whom 731 (207 women) developed type 2 diabetes over the follow-up. Cumulative exposure to low socioeconomic status from childhood to middle age was associated with an increased risk of developing type 2 diabetes in adulthood (hazard ratio [HR] = 1.96, 95% confidence interval: 1.48–2.58 for low cumulative lifecourse socioeconomic score and HR = 1.55, 95% confidence interval: 1.26–1.91 for low-low socioeconomic trajectory). 25% of the excess risk associated with cumulative socioeconomic adversity across the lifecourse and 32% of the excess risk associated with low-low socioeconomic trajectory was attributable to chronically elevated inflammation (95% confidence intervals 16%–58%).
In the present study, chronic inflammation explained a substantial part of the association between lifecourse socioeconomic disadvantage and type 2 diabetes. Further studies should be performed to confirm these findings in population-based samples, as the Whitehall II cohort is not representative of the general population, and to examine the extent to which social inequalities attributable to chronic inflammation are reversible.
Worldwide, more than 350 million people have diabetes, a metabolic disorder characterized by high amounts of glucose (sugar) in the blood. Blood sugar levels are normally controlled by insulin, a hormone released by the pancreas after meals (digestion of food produces glucose). In people with type 2 diabetes (the commonest form of diabetes) blood sugar control fails because the fat and muscle cells that normally respond to insulin by removing sugar from the blood become insulin resistant. Type 2 diabetes, which was previously called adult-onset diabetes, can be controlled with diet and exercise, and with drugs that help the pancreas make more insulin or that make cells more sensitive to insulin. However, as the disease progresses, the pancreatic beta cells, which make insulin, become impaired and patients may eventually need insulin injections. Long-term complications, which include an increased risk of heart disease and stroke, reduce the life expectancy of people with diabetes by about 10 years compared to people without diabetes.
Why Was This Study Done?
Socioeconomic adversity in childhood seems to increase the risk of developing type 2 diabetes but why? One possibility is that chronic inflammation mediates the association between socioeconomic adversity and type 2 diabetes. Inflammation, which is the body's normal response to injury and disease, affects insulin signaling and increases beta-cell death, and markers of inflammation such as raised blood levels of C-reactive protein and interleukin 6 are associated with future diabetes risk. Notably, socioeconomic adversity in early life leads to exaggerated inflammatory responses later in life and people exposed to social adversity in adulthood show greater levels of inflammation than people with a higher socioeconomic status. In this prospective cohort study (an investigation that records the baseline characteristics of a group of people and then follows them to see who develops specific conditions), the researchers test the hypothesis that chronically increased inflammatory activity in individuals exposed to socioeconomic adversity over their lifetime may partly mediate the association between socioeconomic status over the lifecourse and future type 2 diabetes risk.
What Did the Researchers Do and Find?
To assess the extent to which chronic inflammation explains the association between lifecourse socioeconomic status and type 2 diabetes incidence (new cases), the researchers used data from the Whitehall II study, a prospective occupational cohort study initiated in 1985 to investigate the mechanisms underlying previously observed socioeconomic inequalities in disease. Whitehall II enrolled more than 10,000 London-based government employees ranging from clerical/support staff to administrative officials and monitored inflammatory marker levels and type 2 diabetes incidence in the study participants from 1991–1993 until 2007–2009. Of 6,387 participants who were not diabetic in 1991–1993, 731 developed diabetes during the 18-year follow-up. Compared to participants with the highest cumulative lifecourse socioeconomic score (calculated using information on father's occupational position and the participant's educational attainment and occupational position), participants with the lowest score had almost double the risk of developing diabetes during follow-up. Low lifetime socioeconomic status trajectories (being socially downwardly mobile or starting and ending with a low socioeconomic status) were also associated with an increased risk of developing diabetes in adulthood. A quarter of the excess risk associated with cumulative socioeconomic adversity and nearly a third of the excess risk associated with low socioeconomic trajectory was attributable to chronically increased inflammation.
What Do These Findings Mean?
These findings show a robust association between adverse socioeconomic circumstances over the lifecourse of the Whitehall II study participants and the risk of type 2 diabetes and suggest that chronic inflammation explains up to a third of this association. The accuracy of these findings may be affected by the measures of socioeconomic status used in the study. Moreover, because the study participants were from an occupational cohort, these findings need to be confirmed in a general population. Studies are also needed to examine the extent to which social inequalities in diabetes risk that are attributable to chronic inflammation are reversible. Importantly, if future studies confirm and extend the findings reported here, it might be possible to reduce the social inequalities in type 2 diabetes by promoting interventions designed to reduce inflammation, including weight management, physical activity, and smoking cessation programs and the use of anti-inflammatory drugs, among socially disadvantaged groups.
Full Citation:Additional Information
- Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001479.
- The US National Diabetes Information Clearinghouse provides information about diabetes for patients, health-care professionals, and the general public, including information on diabetes prevention (in English and Spanish)
- The UK National Health Service Choices website provides information for patients and carers about type 2 diabetes; it includes peoples stories about diabetes
- The nonprofit Diabetes UK also provides detailed information about diabetes for patients and carers, including information on healthy lifestyles for people with diabetes, and has a further selection of stories from people with diabetes; the nonprofit Healthtalkonline has interviews with people about their experiences of diabetes
- MedlinePlus provides links to further resources and advice about diabetes (in English and Spanish)
- Information about the Whitehall II study is available
Stringhini S, Batty GD, Bovet P, Shipley MJ, Marmot MG, et al. (2013) Association of Lifecourse Socioeconomic Status with Chronic Inflammation and Type 2 Diabetes Risk: The Whitehall II Prospective Cohort Study. PLoS Med 10(7): e1001479. doi:10.1371/journal.pmed.1001479
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Association of Depression With Increased Risk of Severe Hypoglycemic Episodes in Patients With Diabetes
Wayne J. Katon, MD, Bessie A. Young, MD, MPH, Joan Russo, PhD, Elizabeth H. B. Lin, MD, MPH, Paul Ciechanowski, MD, MPH, Evette J. Ludman, PhD, Michael R. Von Korff, ScD
PURPOSE Although psychosocial and clinical factors have been found to be associated with hypoglycemic episodes in patients with diabetes, few studies have examined the association of depression with severe hypoglycemic episodes. This study examined the prospective association of depression with risk of hypoglycemic episodes requiring either an emergency department visit or hospitalization.
METHODS In a longitudinal cohort study, a sample of 4,117 patients with diabetes enrolled between 2000 and 2002 were observed from 2005 to 2007. Meeting major depression criteria on the Patient Health Questionnaire-9 was the exposure of interest, and the outcome of interest was an International Classification of Disease, Ninth Revision code for a hypoglycemic episode requiring an emergency department visit or hospitalization. Proportional hazard models were used to analyze the association of baseline depression and risk of one or more severe hypoglycemic episodes. Poisson regression was used to determine whether depression status was associated with the number of hypoglycemic episodes.
RESULTS After adjusting for sociodemographic, clinical measures of diabetes severity, non–diabetes-related medical comorbidity, prior hypoglycemic episodes, and health risk behaviors, depressed compared with nondepressed patients who had diabetes had a significantly higher risk of a severe hypoglycemic episode (hazard ratio = 1.42, 95% CI, 1.03–1.96) and a greater number of hypoglycemic episodes (odds ratio = 1.34, 95% CI, 1.03–1.74).
CONCLUSION Depression was significantly associated with time to first severe hypoglycemic episode and number of hypoglycemic episodes. Research assessing whether recognition and effective treatment of depression among persons with diabetes prevents severe hypoglycemic episodes is needed.
Katon, WJ, Young, BA, Russo, J, Lin, EHB, Ciechanowski, P, Ludman, EJ, Von Korff, MR. (2013, May/Jun). Association of Depression With Increased Risk of Severe Hypoglycemic Episodes in Patients With Diabetes. Annals of Family Medicine; vol. 11 no. 3, 245-250. doi: 10.1370/afm.1501