Symptoms of anxiety and depression in type 2 diabetes: Associations with clinical diabetes measures and self-management outcomes in the Norwegian HUNT study

Highlights

• Depression is an important risk factor for poor Type 2 diabetes outcomes.

• Depression and anxiety frequently co-occur, but anxiety is rarely accounted for in these studies.

• Our results suggest that depression and anxiety are differentially associated with key diabetes measures.

• Sex-related differences in these associations were noted (i.e., CRP in women and glycemic control in men).

Abstract

Objective

To determine if symptoms of depression and anxiety are differentially associated with clinical diabetes measures and self-management behaviours in individuals with Type 2 diabetes, and whether these associations vary by patient sex.

Research design and methods

A cross-sectional analysis using data from 2035 adults with Type 2 diabetes in the Nord-Trøndelag Health Study. Multivariate logistic regression was used to explore associations between symptoms of depression and anxiety and waist girth, HDL cholesterol, systolic blood pressure, triglycerides, c-reactive protein, glycemic control, diet adherence, exercise, glucose monitoring, foot checks for ulcers, and the subjective patient experience. Analyses were stratified by sex.

Results

Depression was associated with a lower likelihood of avoiding saturated fats (OR = 0.20 [95% CI: 0.06, 0.68]) and increased odds of physical inactivity (OR = 1.69 [95% CI: 1.37, 2.72]). Anxiety was associated with increased odds of eating vegetables (OR = 1.66 [95% CI: 1.02, 2.73]), and an over two-fold increase of feeling that having diabetes is difficult. In women, anxiety was associated with elevated c-reactive protein levels (OR = 1.57 [95% CI: 1.05, 2.34]). In men, depressive symptoms were associated with elevated HbA1c (OR = 5.00 [95% CI: 1.15, 8.23).

Conclusions

Symptoms of depression and anxiety were differentially associated with some key diabetes-related measures. Our results suggest sex-specific differences with respect to two important clinical outcomes (i.e., anxiety and CRP in women and depression and glycemic control in men). These findings should alert practitioners to the importance of detection and management of psychological symptoms in individuals with Type 2 diabetes.

Introduction

Type 2 diabetes represents an increasing global health challenge, due to its growing prevalence worldwide and the chronic complications and functional impairment associated with this condition. Patients with Type 2 diabetes frequently suffer from unipolar depression and anxiety, at rates at least double those observed in diabetes-free populations (Golden et al., 2017, Semenkovich et al., 2015). There is increasing evidence that psychosomatic processes contribute to a range of Type 2 diabetes outcomes, and unipolar depression has been shown to influence the management and prognosis of Type 2 diabetes through adverse effects on factors such as glycemic control (Cherrington et al., 2010), self-care behaviours (Safren et al., 2014), and body mass index (de Wit et al., 2009). In line with this, the presence of comorbid depression in diabetes patients often leads to increased health-care costs, higher risks of vascular complications (Black et al., 2003, Lin et al., 2010), and excess mortality rates (Lin et al., 2004).

Although anxiety disorders often co-occur with depression, anxiety is a far less well understood comorbidity of diabetes. One notable limitation of studies in this area is that they tend to focus on one disorder type at a time, while failing to account for the presence of the other (Demakakos et al., 2014, Demakakos et al., 2010, Gale et al., 2010, Nichols and Moler, 2011). This makes it particularly challenging to assess the scope of the impact of anxiety disorders (or indeed, depression) on diabetes-related outcomes. Both psychiatric disorders share a significant overlap of features (e.g., generalized distress and low serotonin levels (Baldwin and Rudge, 1995)), and over 40% of Type 2 diabetes patients presenting with major or minor depression in primary care settings are diagnosed with a concurrent anxiety disorder (Golden et al., 2017). However, depression and anxiety also display important phenotypic differences. Whereas depression is uniquely associated with anhedonia and physiological responses such as lethargy and fatigue, anxiety is marked by excessive worry and physiologic hyperarousal such as trembling, sweating, and muscle tension (Gelenberg, 2000, Zbozinek et al., 2012). Evidence suggests that, like depression, anxiety may have important associations with diabetes outcomes such as an increased risk of hypertension, inflammation, and glycemic control (Anderson et al., 2002, Vogelzangs et al., 2013). It is also evident that important sex differences may exist with respect to these associations; for example, depression has been linked to poor glycemic control in men, but not women (Cherrington et al., 2010). Similar results have been noted with respect to anxiety disorders and risks of heightened inflammation in men (Vogelzangs et al., 2013).

The experience of concurrent symptoms of anxiety and depression is also associated with worse treatment outcomes than either disorder alone, including poorer adherence to treatment, higher costs, and lower quality of life (Hofmeijer-Sevink et al., 2012). Recent research in patients with cancer demonstrated that concurrent anxiety-depression was present in over 60% of patients with depression, and that this phenotype was only associated with specific cancer subtypes (Brintzenhofe-Szoc et al., 2009). To our knowledge, no similar research has been conducted with respect to affective symptom phenotypes and diabetes outcomes. By failing to adequately differentiate between these phenotypes, existing studies may link complications related to the presence of anxiety or its correlates erroneously to depression, or vice versa. A proper understanding of these relationships may inform the development of more refined and integrated approaches to treatment in the future, as certain affective symptom phenotypes may be more relevant to specific Type 2 diabetes outcomes, and these associations could vary across patient populations.

The purpose of this study was to investigate the mutually exclusive associations between symptoms of depression and/or anxiety and several important clinical and behavioural outcomes in Type 2 diabetes, as well as to document any variations in patient outcomes by sex.