Original article
The role of depression and anxiety in onset of diabetes in a large population-based study

https://doi.org/10.1016/j.jpsychores.2006.07.009Get rights and content

Abstract

Objective

Recent research has shown that depression may predict incident diabetes. The aims of the study are to investigate if symptoms of depression and anxiety precede the onset of diabetes or vice versa and to examine if mediating factors may explain such associations.

Methods

A prospective population-based study (N=37,291) investigating the associations between symptoms of depression/anxiety and diabetes was conducted.

Results

Individuals reporting symptoms of depression and anxiety at baseline had increased risk of onset of type 2 diabetes at 10-year follow-up. No gender differences were found. The analyses did not reveal underlying factors that mediated the association. Baseline diagnosis of diabetes was not associated with subsequent symptoms of anxiety or depression among males or females.

Conclusion

Diabetes did not predict symptoms of depression or anxiety. Symptoms of depression and anxiety emerged as significant risk factors for onset of type 2 diabetes independent of established risk factors for diabetes, such as socioeconomic factors, lifestyle factors, and markers of the metabolic syndrome. The comorbidity between depression and anxiety may be the most important factor.

Introduction

The prevalence of depression among patients with diabetes is higher than in the general population [1], [2]. The odds of depression have been estimated to be twice that of the nondiabetic population [1]. There has been less focus on anxiety in patients with diabetes, yet a meta-analysis [3] showed increased prevalence of symptoms of anxiety and generalised anxiety disorders.

The reasons for higher prevalence rates of depression and anxiety are not fully understood. There are two hypotheses about possible relationships [4]. The first regards mood disturbance as being manifestations of direct physiological effects of diabetes. The second hypothesis sees mental symptoms as stemming from the stresses and strains of having a chronic somatic condition. Recently, some studies suggest depression precedes diabetes and increases the risk of developing type 2 diabetes [5], [6], [7], [8], [9], [10], [11], [12], [13]. These findings are consistent with research outside the field of diabetes, which has shown that depression and anxiety predict subsequent morbidity [14], [15].

In prior research, which mainly has been cross-sectional, mental symptoms have been considered a consequence of diabetes, yet the association between diabetes and subsequent development of depression or anxiety has not been explored in longitudinal perspectives.

One study has investigated if depression or anxiety may predict type 1 diabetes and found no such associations [16]. Nine studies with population-based longitudinal data suggest that depression predict the onset of type 2 diabetes [5], [6], [7], [8], [9], [10], [11], [12], [13]. Two studies did not find any relations [16], [17]. The majority of these studies relied on self-reported measures to identify mental symptoms and diabetes. Some of the studies involved rather homogenous samples [6], [10], [12], and some included small sample sizes [5], [6], [9], [10], which may have limited the generalisability. Only one of these studies investigated a number of metabolic factors as possible mediators in the development of type 2 diabetes [8].

The mechanisms that underlie the associations between depression and onset of type 2 diabetes are unclear. Symptoms of depression may predict diabetes independently or through established risk factors for diabetes. Lifestyle factors, metabolic factors, and neuroendocrinological factors have been linked to increased risks of developing diabetes in individuals with depressive symptoms. Possible mechanisms include the influence of depressive symptoms on behavioural factors, such as sedentary lifestyles, smoking, and overeating, resulting in metabolic disturbances, which may explain the onset of diabetes. Altered activities in the hypothalamic–pituitary–adrenal (HPA) axis with cortisol elevations during depressive episodes, which affect approximately half of all patients [18], may also increase the risk of type 2 diabetes.

More population-based studies are needed to establish a temporal relationship between depression and types 1 and 2 diabetes, as well as possible mechanisms to explain the connections [19]. The aims of this study are, first, to investigate if symptoms of depression and anxiety predict onset of diabetes or vice versa and, second, to explore whether the potential links are mediated by risk factors related to diabetes or symptoms of depression and anxiety.

Section snippets

Study population

This investigation draws data from two large health studies in Norway, HUNT-1 and HUNT-2 (Nord-Trøndelag Health Studies, www.hunt.ntnu.no). All inhabitants of Nord-Trøndelag County aged 20 years and above received invitations to participate in the first and second health study. Of the total population in the county, 74,997 individuals attended HUNT-1 in 1984–1986 (88.1%) and 65,648 individuals attended HUNT-2 in 1995–1997 (71.3%).

In HUNT-1, blood pressure, height, and weight were measured, and

Results

Table 1 shows the sociodemographic, lifestyle, metabolic, and clinical characteristics at follow-up of the 37,291 individuals who participated in both health surveys. A total of 8311 (22.3%) had symptoms of depression and anxiety (ADI) at baseline. Among those with a positive ADI, the prevalence of newly developed type 2 diabetes (2.5%) was significantly higher over the 10-year follow-up as compared to the prevalence among those without symptoms of anxiety and depression (1.6%) (P<.001).

Discussion

This study had three major findings. First, we did not find increased risk for developing depression or anxiety in those who reported diabetes at baseline. Second, symptoms of anxiety and depression were associated with onset of type 2 diabetes, but not type 1 diabetes. There were no gender differences. Finally, the analyses did not reveal underlying factors that mediated the association between symptoms of depression and anxiety and subsequent type 2 diabetes.

Depression is prevalent in

Acknowledgments

Nord-Trøndelag Health Study (The HUNT Study) is a collaboration between HUNT Research Centre, Faculty of Medicine, Norwegian University of Science and Technology (NTNU, Verdal), Norwegian Institute of Public Health, and Nord-Trøndelag County Council.

References (35)

  • N Kawakami et al.

    Depressive symptoms and occurrence of type 2 diabetes among Japanese men

    Diabetes Care

    (1999)
  • MR Carnethon et al.

    Symptoms of depression as a risk factor for incident diabetes: findings from the National Health and Nutrition Examination Epidemiologic Follow-up Study, 1971–1992

    Am J Epidemiol

    (2003)
  • SH Golden et al.

    Depressive symptoms and the risk of type 2 diabetes: the Atherosclerosis Risk in Communities study

    Diabetes Care

    (2004)
  • SA Everson-Rose et al.

    Depressive symptoms, insulin resistance, and risk of diabetes in women at midlife

    Diabetes Care

    (2004)
  • LA Palinkas et al.

    A prospective study of type 2 diabetes and depressive symptoms in the elderly: the Rancho Bernardo Study

    Diabet Med

    (2004)
  • M van den Akker et al.

    Is depression related to subsequent diabetes mellitus?

    Acta Psychiatr Scand

    (2004)
  • C Arroyo et al.

    Depressive symptoms and risk of type 2 diabetes in women

    Diabetes Care

    (2004)
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