The current literature assessing the management of type II diabetes for individuals with schizophrenia and schizoaffective disorders has indicated that there are a number of tactics used to manage blood glucose levels. One that has drawn attention involves changing the antipsychotics prescribed. Antipsychotics have been the focus because of the weight gain and glucose intolerance that is associated with use of these medications [4
]. A meta-analysis conducted by Barnett et al. [10
] reported that patients treated with clozapine and olanzapine have higher rates of weight gain and therefore increased diagnosis of type II diabetes compared to other antipsychotics. Consistent with these findings are case studies that changed antipsychotic medications as an intervention to manage blood glucose in type II diabetes. Lerner et al. [27
] lowered the dose of olanzapine for two patients and noted a reduction in blood glucose levels. Furthermore, a total of four case studies observed a remission of type II diabetes upon the replacement of olanzapine with risperidone, as HbA1c levels normalized [28
]. Given the impact of antipsychotic medications in the development of this disease, recommendations are often made to change prescriptions if persistent weight gain and onset of type II diabetes occurs [10
]. However, this treatment approach poses challenges because individuals with schizophrenia may experience a relapse of psychotic or depressive symptoms during the transition period between medications [33
]. Moreover, not every individual has a therapeutic response to all antipsychotics [35
Considering the challenges with changing antipsychotic medication, our SER aimed at determining effective delivery of diet and lifestyle interventions to enable management of type II diabetes in individuals with schizophrenia or schizoaffective disorders. The success of diet and lifestyle interventions to prevent or manage type II diabetes in individuals with and without schizophrenia or schizoaffective disorders has been documented in the literature. Menza et al. [36
] conducted a 12-month lifestyle intervention that combined diet and physical activity in patients with schizophrenia and schizoaffective disorders. Findings included reduced weight and BMI, increased nutritional knowledge, and improved HbA1c levels, thus minimizing risk of type II diabetes development. Torgerson et al. [37
] was successful in preventing the onset of type II diabetes in obese individuals by combining weight loss with the inhibition of an enzyme that breaks down fats. Additionally, Lim et al.'s [38
] paper suggests that weight loss enabled by restricting calories to 600 kcal/day is an effective method to decrease BMI within the general type II diabetes population (P
< 0.05). Calorie restriction also corresponded to greater blood glucose control, as glycated hemoglobin decreased to normal levels in 8 weeks (P
While the relationship between lifestyle interventions with weight loss and improved glycated hemoglobin is well documented, the most effective way of delivering DSME is not always clear for individuals with schizophrenia or schizoaffective disorders. Therefore, our paper makes an important contribution to the literature by highlighting effective DSME strategies to support the integration of healthy habits into lifestyle. Each DSME lifestyle intervention reviewed in our paper observed reduced weight and BMI in the presence of intervention strategies that addressed the challenges associated with schizophrenia, such as decreased cognitive ability, reduced motivation and limited access to resources [6
]. Additionally, Lindenmayer et al. [24
] and Teachout et al. [25
] observed that diet can reduce fasting blood glucose.
One drawback consistent in all interventions was the absence of finding statistical significance when HbA1c levels were reduced. One likely explanation is the fact that interventions were not long enough to observe changes in HbA1c levels [23
]. This is because retrieving an accurate measure may require blood glucose to be controlled for more than three months. If lifestyle changes were not fully adopted, it would be more difficult to see a reduction in HbA1c, even if some changes occurred. In contrast, blood glucose measures depict blood glucose at one point in time and this value can fluctuate hourly. Thus, HbA1c is considered a more reliable measure of overall blood glucose control. Additionally, HbA1c has been correlated with diabetes complications, while blood glucose has not [39
Because all quality ratings of the analyzed studies resulted in excellent and good assessments, there is a strong level of evidence to support our conclusion made in this SER [40
]. However, while the findings of this paper indicate that lifestyle interventions positively impact type II diabetes management, there were limitations associated with the heterogeneity of the study settings included in the analysis. In the psychiatric inpatient setting, participation in the interventions was structured in the individual's daily routine. Conversely, in McKibbin et al.'s [23
] study, recruitment from community clubhouses and board-and-care facilities indicates that participant involvement required a greater level of self-motivation. Therefore, care needs to be taken if inpatient interventions are adapted in outpatient settings, because individuals within the community may have limited access to fitness resources, such as gym equipment and safe areas to exercise.
As a result of limiting searches to four databases containing primarily peer-reviewed material, a potential publication bias is an additional limitation of this SER. However, the databases searched covered an extensive scope of clinical disciplines that were relevant for the nature of the research question: PsycINFO captures psychological literature, CINAHL retrieves the nursing and allied health, Medline contains medical literature, while ISI Web of Science is multidisciplinary. Additionally, while grey literature was not searched for directly, PsycINFO includes doctoral theses available in Dissertations Abstracts International. Additionally, due to a lack of fluency in languages other than English, French, Italian and Greek, papers in other languages were not considered.
While the analyzed studies indicate the short-term effectiveness of lifestyle interventions in individuals with type II diabetes and schizophrenia, the long-term sustainability of treatment outcomes has not been explored. Additionally, it has been observed that such lifestyle interventions are effective for older adults with type II diabetes and schizophrenia. However, the success of such approaches within the first episode population is unknown. Although adults over 40 years of age are an important population to consider due to the increased risk factors of diabetes from long-term use of antipsychotics and being over the age of 45, the onset of type II diabetes in individuals aged 20 to 49 years is increasing [12
]. Therefore, an additional recommendation for future research involves determining the effectiveness of such programs for youth and young adults experiencing early-onset psychosis who also have type II diabetes.
Overall, the current state of the literature suggests promise within this line of inquiry. However, our review also indicates that there are gaps in the current literature. Of additional significance is the need for interdisciplinary teams when addressing the complex health concerns associated with both schizophrenia and type II diabetes [12