Improved Glycemic Control in Adults with Serious Mental Illness and Diabetes with a Behavioral and Educational Intervention

Abstract

Objective:

The purpose of this study was to evaluate a 16-week, reverse integrated care, behavioral and educational group intervention for individuals with serious mental illness and diabetes.

Methods:

Primary outcome was change in glycated hemoglobin (HbA1c). Secondary outcomes included body mass index (BMI), blood pressure, lipids, physical activity, diabetes knowledge and self-care.

Results:

Thirty-five participants attended at least 1 group and were included in a modified intent-to-treat analysis. From baseline to week 16, HbA1c improved, 7.5±1.6 to 7.1±1.4, p=0.01, BMI improved, 33.3±3.8 to 32.9±4.1, p<0.001, as did measures of diabetes knowledge and self-care. One-year follow up in a subset showed no evidence for rebound in HbA1c.

Conclusions:

This 16-week behavioral and educational group intervention resulted in improvements in glycemic control, BMI, diabetes knowledge and self-care. The results warrant larger-scale, controlled trial testing of this intervention to improve diabetes-related health outcomes in those with serious mental illness.

Introduction

Adults with schizophrenia in the US die on average 28 years earlier than those in the general population, a mortality disparity largely attributable to cardiometabolic and pulmonary disease (1). It is estimated that 13% of people with serious mental illness have diabetes compared to 6% of the general population (2). Poor understanding of diabetes self-management, including diet and physical activity goals, are modifiable factors contributing to the morbidity and mortality associated with diabetes in those with serious mental illness (3). Randomized controlled trials of combined diabetes education and self-management interventions in those with serious mental illness and diabetes to date have not reported significantly improved glycemic control (4, 5). Effective, scalable, evidence-based interventions that improve glycemic control are needed to reduce morbidity and mortality in this population.

We tested a behavioral and educational group intervention for individuals with co-morbid serious mental illness and diabetes focused on practical strategies to address social, economic, and behavioral determinants of health to advance patient knowledge, motivation, skills, and self-efficacy for managing diabetes. This intervention delivered a medically-focused intervention in a community mental health center setting familiar to participants. The primary outcome was improved glycemic control, as measured by glycated hemoglobin (HbA1c). Secondary outcomes included body mass index (BMI), blood pressure, lipids, physical activity, and diabetes knowledge and self-care. A 12-month follow-up was conducted to assess durability of the effect.

Methods

This study was approved by the Partners Healthcare Institutional Review Board. Participants demonstrated competence to consent via a written assessment of protocol knowledge and participation requirements and gave informed consent prior to participating in study procedures. Data were collected between 2/1/2016 and 10/31/2018.

Participants

Adult outpatients with serious mental illness at an urban community mental health center and nearby clubhouse day program were identified who had HbA1c ≥ 6.5 (n=43), or HbA1c ≥ 6.0 and taking metformin (n=24), or diagnosis of type 1 or 2 diabetes in the medical record (n=13). Those who were non-English speaking or deaf were excluded. The study was supported by a one-year grant that was renewed, providing a second year of funding. Thirty participants were enrolled at the beginning of each year of grant funding and randomly assigned to initial or delayed (four months later) start (See Online Supplement for Consort Diagram). Mean age of those enrolled (n=60) was 55 years (SD=11.4), 70% were male, 53% white, 28% black, 17% ‘other’ race, and 2% Hispanic.

Intervention

The intervention consisted of 16 weekly 60-minute group meetings. Sessions were co-led by a psychologist specializing in health behavior change in those with serious mental illness and a psychiatry resident. Guest co-leaders included a diabetologist, an internist with behavioral weight management expertise, and a registered dietician. Five manualized content modules were developed by a team including physicians from Psychiatry, General Internal Medicine, and the Diabetes Center, and covered basic diabetes disease education and management, nutrition, exercise, stress management, and positive psychology topics, modeled on content from the Diabetes Prevention Program (DPP) (See Online Supplement for DPP curriculum). A pedometer capable of storing seven days of step counts was provided. During each group meeting, participants received a healthy lunch and $3 to help to defray public transportation costs. Group outings to nearby grocery stores, hospital cafeteria, and Department of Mental Health gym provided participants with education on nutrition and physical activity available in accessible community settings and enabled participants to practice disease self-management skills.

Core features of the group intervention curriculum included interactive education and problem solving informed by challenges presented by each participant’s home community (i.e. tendency to shop at convenience stores, access to refrigeration, frequent fast food). The intervention was informed by the Self Determination Theory (SDT) of motivation (6), emphasized resilience enhancement, and focused on increasing access to positive emotions and maximizing self-confidence, autonomy, and connection, with the goal of increasing intrinsic motivation, persistence, and goal acquisition (7). Group leaders employed a directive approach to assist participants in setting a weekly SMART (specific, measurable, achievable, realistic, timed) behavior goal (8) related to the weekly discussion topic (i.e. achieving a daily step count goal during exercise modules, eliminating sugar-sweetened beverages during diet modules). Each group included follow-up on each participant’s goal from the prior week and setting of an individualized behavioral goal for the coming week.

Assessments

The primary outcome was change in HbA1c from baseline to week 16. Secondary outcomes included BMI (weight was measured weekly in light clothing without shoes), systolic and diastolic blood pressure (seated, at rest, measured weekly), serum lipid concentrations (low density lipoprotein (LDL), high density lipoprotein (HDL), triglycerides (TG), total cholesterol (TC), measured at baseline and week 16), daily step count (measured by study-provided pedometer), and diabetes knowledge and self-management (Short Diabetes Knowledge Instrument (SDKI), Summary of Diabetes Self-Care Activities (SDSCA), and Problem Areas in Diabetes (PAID), assessed every four weeks). As most participants did not fast prior to their lipid panel measurement, limiting TG and LDL measurement validity, we report only TC and HDL. The Clinical Global Impressions Scale (CGI) severity (range 1–7) was assessed for each patient at baseline by three independent clinicians and averaged. See online supplement for assessment citations.

Analyses

A modified intention-to-treat (ITT) analysis (9) was performed that included all participants who attended at least one group meeting (n=35). For dependent variables, a linear model with a random intercept for subjects was fit to the data, thereby controlling for dependencies due to repeated measures. Fixed effects included a linear trend to estimate the change during intervention and coefficient to estimate change post-intervention where applicable. Bayesian mixed effects modeling was conducted using the R package “rstanarm” (version 2.13.1, Stan Development Team, 2016) to estimate the effect of the intervention on outcomes of interest. Effects were considered significant if p-values were less than 0.022 (the lower boundary for a two-sided test after controlling for Monte Carlo approximation error). Missing data were assumed to be missing at random and thus were handled by the hierarchical nature of the mixed effects models. In instances in which model assumptions (e.g., normally distributed residuals) were violated, a mixed effects model robust to outliers (based on the student t distribution) was used instead. (See Online Supplement for assessment of model performance). For participants with a delay of four months between enrollment and study start, change in HbA1c was assessed via a paired samples t-test, to serve as a control.

Results

Participants

Two-hundred sixty-two individuals were screened via medical record review by community mental health center staff (SM) for study eligibility. Eighty potential participants met inclusion criteria; sixty participants provided informed consent and were enrolled. Thirty-five individuals attended one or more group sessions and were included in the modified intent-to-treat (ITT) analysis. (See Online Supplement for Consort Diagram)

In the modified ITT sample of participants who attended at least one group, average attendance was 11.5±6.5 group sessions (72%); two participants attended one group, eight attended 2–8 groups, and twenty attended 9–16 groups. Mean age was 53 years, 77% were male, 46% white, 34% black, 20% ‘other’ race, and 3% Hispanic. Ninety-seven percent were taking any antipsychotic medication, 63% were taking clozapine or olanzapine, 66% were taking metformin, 34% were taking other oral diabetes medication, and 26% were taking insulin. Mean baseline HbA1c was 7.5±1.6% and mean BMI was 33±3.8 kg/m². Thirty-five percent had systolic blood pressure ≥130 mmHg, and 51% had diastolic blood pressure ≥80 mmHg. Mean CGI severity rating was 4.8±0.9. There were no noted significant differences between the modified ITT sample of participants who enrolled and attended at least one group and those who enrolled but attended no groups. (See Online Supplement for Baseline Characteristics Table)

Outcomes

In the modified ITT sample (n=35), HbA1c was 7.5±1.6% at baseline and 7.1±1.4% at week 16, β=−0.6, SD=0.25, p=0.01. In the sample with a delay of four months from enrollment to start of study procedures (n=16), HbA1c values did not differ significantly between enrollment, 7.8±2.3%, and the start of intervention, 7.6±1.7%, a difference of −0.2 (t(15)=−0.02, p=0.99). For participants who enrolled but attended no groups HbA1c was 6.5±1.1% at baseline and 6.4±0.8% after 16 weeks, β=−0.46, SD=0.47, p=0.156.

Mean BMI was 33.3±3.8 kg/m² at baseline and 32.9±4.1 kg/m² at week 16, β=−0.76, SD=0.17, p<0.001. Diabetes knowledge improved from 7.2±2.7 at baseline to 8.5±2.7 at week 16, β=1.75, SD=0.42, p<0.001, as did days spent observing general (p=0.003) and specific diet self-care (p=0.001), and exercise self-care (p=0.015). Total cholesterol, HDL, systolic and diastolic blood pressure, steps per day, foot selfcare, and diabetes distress did not change.

Nine of the 15 participants enrolled in year one who attended at least one group remained in the clinic for one year after the end of the group intervention and provided one-year follow-up data. HbA1c in this subgroup was 7.1±1.3% at end of treatment and 7.1±1.7% after one-year follow up.

Discussion

Adults with serious mental illness and diabetes who participated in at least one session of a 16-week group behavioral and educational intervention for diabetes self-management (n=35) had significant improvement in glycemic control. While this was an open label intervention that must be replicated in a controlled trial, confidence in this result is increased by the observation that A1C did not significantly change for individuals prior to intervention start, enrolled participants who attended no group sessions had no significant change in HbA1c in the four months following enrollment, and reduction in HbA1c during the intervention appeared to be durable one year after enrollment. Significant improvements in BMI, weight, diabetes knowledge, and diet and exercise self-care are also notable.

These improvements occurred in a study population who were psychiatrically stably but significantly symptomatic; 63% were taking clozapine or olanzapine, antipsychotic medications with the greatest metabolic adverse effects. This finding, if replicated, suggests that diabetes education and behavioral interventions in a psychiatric care setting could significantly improve glycemic control and associated medical risk factors in a vulnerable population with an almost 30-year mortality disparity.

While these results are derived from an open label trial and should be interpreted cautiously for that reason, they do stand in contrast to the two randomized controlled trials of behavioral and educational interventions for individuals with schizophrenia and diabetes of which we are aware that did not report significant HbA1c reduction (4, 5). Sajatovic and colleagues compared usual primary care with Targeted Training in Illness Management (TTIM), consisting of 12 weekly educational group sessions delivered in a primary care setting followed by 48 weeks of brief telephone maintenance sessions, in 200 participants with serious mental illness and diabetes. Those assigned to TTIM demonstrated increased diabetes knowledge and improved psychiatric symptoms and functioning but no significant effect on HbA1c, BMI, or blood pressure (5). McKibbin and colleagues assigned 57 participants with diabetes and schizophrenia-spectrum illness to receive Diabetes Awareness and Rehabilitation Training (DART), a 24-week group diabetes education, nutrition, and lifestyle exercise intervention, or usual care plus three educational brochures on diabetes (4). As in our intervention, DART included weekly weigh-ins, pedometers, healthy food samples, and reinforcements for attendance and behavior change. Consistent with our results, participants assigned to DART had significantly reduced weight, improved diabetes knowledge and self-efficacy, and increased physical activity scores that were sustained at 12-month follow-up, but did not demonstrate significant improvements in HbA1c (10).

Among those who attended at least one group, average attendance was 11.5 of 16 sessions (72%), indicating good retention of those who engaged in any sessions. Over half of those who gave informed consent (58%) attended ≥1 group. Co-location of the group intervention in the community mental health center where participants were regularly attending behavioral health appointments, as opposed to primary care or research settings in the studies by McKibbon and Sajatovic, respectively, and receipt of incentives for being a part of the group program (e.g., healthy free lunch, pedometer, and $3 for attendance) likely improved retention.

In contrast to classical motivational interviewing approaches, group leaders in our intervention employed a directive, at times prescriptive approach to assist with goal-setting, providing clear recommendations and praise for behavior change efforts and group engagement. This, together with active weekly behavioral goal follow-up for progress on evolving, individualized, environmentally-informed, actionable goals, and goal evolution, may have impacted participant success. The intervention took into account barriers identified by participants to purchasing and preparing healthy food (e.g., lack of food storage options, tendency to shop at convenience stores) and to exercise (e.g., paranoia, unsafe neighborhoods) and addressed these barriers in concrete ways through group problem solving exercises. A qualitative study is underway to identify factors impacting engagement in this population, determine key messages retained, and identify areas for improvement.

There are important limitations to consider in evaluating this study. This was an open label study of the effect of fixed enrollment groups with no treatment as usual control. Nearly sixty percent of those who enrolled participated in at least one group. As approximately forty percent of those consented attended no groups, results are generalizable to individuals who are willing to at least initiate participation in an intervention, rather than all with serious mental illness and diabetes. We speculate that the delay of up to 20 weeks between consent and initiation of the intervention for half the cohort due to funding and staffing limitations likely contributed to attrition. Participants who attended at least one group may have been more motivated to make positive health behavior changes. Though medication optimization was not an intervention in the study, participants may have sought intervention from their primary care team as a result of study participation, thus we cannot definitively isolate the effects to the behavioral intervention. The intervention was delivered by a highly trained psychologist and psychiatrist; future studies will evaluate our ability to replicate these results with alternate staffing models (e.g. community health workers or peer specialists).

Conclusions

A 16-week behavioral and educational group intervention improved modifiable health behaviors that underlie the large morbidity and mortality disparity in those with serious mental illness and diabetes. Improvements were noted in objective measures of glycemic control, BMI, weight, and diabetes knowledge and self-care among adults with diabetes and serious mental illness who attended at least one group. Encouraging evidence for maintenance of this effect over one year was also observed. These results warrant further testing relative to a control with the goal of discovering an intervention that is effective and scalable to mitigate the large public health impact of suboptimal diabetes care in this vulnerable population.

Highlights.

• -Participants in an open 16-week, reverse integrated care, behavioral and educational group intervention demonstrated significant improvement in glycemic control, BMI, and diabetes knowledge and self-care.
• -A group behavioral and educational intervention may produce meaningful improvements in important clinical outcomes among the most medically high-risk patients in a psychiatrically ill cohort.
• -Improvements in glycemic control were maintained in those with one-year follow-up data.