The prevalence of diabetes mellitus and abnormal glucose metabolism in the inpatient psychiatric setting: A systematic review and meta-analysis

Abstract

Objective

To systematically determine the prevalence of diabetes mellitus (DM), impaired fasting glucose (IFG), and impaired glucose tolerance (IGT) in psychiatric inpatients and explore the impact of patient and study variables on prevalence estimates.

Method

We searched EMBASE, PsychINFO, Medline and CENTRAL from database inception until 1st December 2015. We included studies of any design reporting prevalence of abnormal glucose metabolism in any adult psychiatric inpatients. We conducted a random effects meta-analysis to generate pooled prevalence estimates. Chi-square tests compared differences within categorical variables (inpatient setting, continent of study and patient diagnostic category) and Spearman's correlation analyses assessed the impact of linear variables (age, year of data collection and study quality). Study quality was assessed using an adapted Newcastle-Ottawa Scale.

Results

36 study reports representing 42 unique cohorts were included. Across all studies prevalence of unspecified type DM was 10% (95%CI: 9–12), of T1DM was 1% (0–1), of T2DM was 9% (6–13), of IFG 18% (8–28), and of IGT was 22% (16–28). These estimates were not affected by study quality.

Conclusions

All estimates are higher compared to the general population. Mental health professionals should be aware of this elevated prevalence to improve screening and management of abnormal glucose metabolism.

Introduction

The prevalence of diabetes mellitus (DM) and abnormal glucose metabolism is often reported as higher in psychiatric inpatients compared to the general population, [1] and as a co-morbidity has been associated with an increased length of stay [2]. Psychiatric patients with abnormal glucose metabolism have poorer long-term outcomes including increased tendency to relapse of mental illness, [3], [4] and increased mortality secondary to an increased risk of cardiovascular disease [5]. Appropriate detection and treatment of abnormal glucose metabolism is thus an important target for interventions to improve clinical outcomes in psychiatric inpatients. Reported prevalence estimates for DM in psychiatric inpatients range from 2% to 25% and are often based on small cross-sectional studies, [6], [7] which frequently are limited to subpopulations, including those with particular diagnoses or on particular psychotropic medication [8].

Previous systematic reviews in patients with psychiatric illness have focused on the prevalence of metabolic syndrome, or of exclusively type two diabetes mellitus (T2DM) [9], [10], [11], [12], [13]. Whilst rates of 30–40% [9], [14] of metabolic syndrome, and 7–13% of T2DM [12], [13] are commonly reported they offer no specific detail on prevalence of T1DM or impaired glucose metabolism, and do not focus on the psychiatric inpatient setting. The burden of disease of DM, impaired fasting glucose (IFG), and impaired glucose tolerance (IGT) within the inpatient setting remains uncertain despite these disease states having specific and alternative interventions available as management strategies, with the inpatient setting representing an excellent window of opportunity for both screening and intervention. Improved knowledge and screening for abnormal glucose metabolism has the potential to improve and personalise inpatient psychotropic prescribing regimens leading to fewer diabetogenic prescriptions in those with states of impaired glucose metabolism but without frank diabetes.

As yet no systematic review has provided pooled prevalence estimates of all types of DM, IFG or IGT in psychiatric inpatients despite an increase in the awareness of the need for physical health screening and management of chronic medical conditions in patients with psychiatric illness [15]. With greater emphasis being placed on improving diagnosis and management of co-morbid medical conditions within psychiatric inpatient settings, this study aims to systematically review the literature and fill this gap. We aimed to present a pooled prevalence of DM, IFG and IGT in psychiatric inpatients and to explore the impact of study populations and characteristics on prevalence estimates.