Posttraumatic stress disorder and incidence of type-2 diabetes: a prospective twin study

Abstract

Growing evidence has linked posttraumatic stress disorder (PTSD) to insulin resistance and type-2 diabetes, but most previous studies were cross-sectional. We examined the association between PTSD and incidence of diabetes in a prospective study of middle-aged male twins from the Vietnam Era Twin Registry. Lifetime PTSD was diagnosed at baseline with the Diagnostic Interview Schedule (DIS) according to DSM-III-R criteria. Subthreshold PTSD was defined by meeting some, but not all, criteria for PTSD. A total of 4340 respondents without self-reported diabetes at baseline were included. Of these, 658 reported a new diagnosis of treated diabetes over a median of 19.4 years of follow-up. At baseline, twins with PTSD showed more behavioral and metabolic risk factors such as overweight and hypertension. The age-adjusted cumulative incidence of diabetes was significantly higher in twins with PTSD (18.9%) than those without PTSD (14.4%), [odds ratio (OR) = 1.4, 95% confidence interval (CI) 1.03-1.8], and intermediate in those with subthreshold PTSD (16.4%) (OR = 1.2, 95% CI 0.9-1.5, p for trend = 0.03). Adjustment for military, lifestyle and metabolic factors diminished the association. No significant association was found comparing twin pairs discordant for PTSD. In conclusion, PTSD was prospectively associated with a 40% increased risk of new-onset type-2 diabetes which was partially explained by a cluster of metabolic and behavioral risk factors known to influence insulin resistance. Shared biological or behavioral precursors which occur within families may lead to both PTSD and insulin resistance/diabetes. Thus, PTSD could be a marker of neuroendocrine and metabolic dysregulation which may lead to type-2 diabetes.

Keywords: Diabetes; Epidemiology; Posttraumatic stress disorder; Stress; Twin studies.

Copyright © 2014 Elsevier Ltd. All rights reserved.

Figures

Figure 1

Eligibility for Prospective Cohort Study of the Association of PTSD and Incident Diabetes

Figure 2

Association of PTSD with Age-Adjusted Incident Diabetes According to Vietnam Theater Service. Footnotes to Figure 2: N/S: No PTSD vs. Subthreshold PTSD N/P: No PTSD vs. PTSD No PTSD is defined as having no lifetime history of PTSD at the 1992 interview. PTSD is defined as having a lifetime history of PTSD at the 1992 interview. Subthreshold PTSD is defined as meeting both the A and B criteria and either the C or D criteria for PTSD according to the DSM-IIIR. All estimates are weighted for non-response.