The authors’ observations
Pharmacotherapy for patients with comorbid schizophrenia and diabetes requires consideration of clinical and psychosocial factors unique to this population.
Antipsychotic choice
Selection of an antipsychotic agent to address psychosis requires considering its efficacy, side-effect profile, and adherence rates, as well as its potential effects on metabolic regulation and weight (Table 1). Typical antipsychotics are less likely than atypical antipsychotics to cause metabolic dysregulation.12 When treatment with atypical antipsychotics cannot be avoided—such as when side effects or an allergic reaction develop—consider selecting a relatively weight-neutral drug with a lower potential for metabolic dysregulation, such as aripiprazole. However, many times, using an agent with significant effects on metabolic regulation cannot be avoided, making treating and monitoring the resulting metabolic effects even more significant.
Glycemic control
Initiating an agent for glycemic control in persons with newly diagnosed diabetes requires weighing many factors, including mode of delivery (oral or subcutaneous), level of glycemic control required, comorbid medical illness (such as renal impairment and heart failure), cost, and potential long-term side effects of the medication (Table 2).13 Oral agents have a slower effect on lowering the blood glucose level, and each agent carries contraindications, but generally they are more affordable. Many present a low risk of hypoglycemia but sulfonylureas are an exception. In addition, metformin could lead to weight loss over the long term, which further lowers the risk of diabetes.
If, however, tight and immediate glycemic control is needed, subcutaneous insulin injections might be required, although this method is more costly, carries an increased risk of hypoglycemic episodes acutely, and leads to weight gain in the long run because of induced hunger and increased appetite.
Psychosocial factors
In addition to the clinical variables above, treating diabetes in patients with comorbid schizophrenia requires considering other psychosocial factors that might not be readily apparent (Table 3). For example, patients with schizophrenia might have decreased motivation, self-efficacy, and capacity for self-care when it comes to health maintenance and medication adherence.14 Chronically mentally ill persons might have reduced cognitive functioning that could affect their ability to maintain complicated medication regimens, such as administering insulin and monitoring blood glucose.
In addition, easy access to hypodermic needles and large amounts of insulin could become a safety concern in patients with ongoing hallucinations, delusions, and thought disorder, despite antipsychotic treatment. For example, a patient with schizophrenia and diabetes who has been maintained on insulin might begin hearing voices that tell her to inject her eyeballs with insulin. Similarly, although the risk of hypoglycemic episodes in patients treated with insulin is well known, patients with schizophrenia have a higher risk of acute complications of diabetes than other patients with diabetes.15Psychosocial factors, such as placement, support system, and follow-up care need to be considered. In some instances, the need to administer daily subcutaneous insulin could be a barrier to placement if the facility does not have the staff or expertise to monitor blood glucose and administer insulin.
If the patient is returning home, then the patient or a caretaker will need to be trained to monitor blood glucose and administer insulin. This might be difficult for persons with chronic mental illness who have lost the support and care of their family. Also, consider the issue of storing insulin, which requires refrigeration. Because of the potential complications involved in using insulin in patients with schizophrenia, practitioners should consider managing non-insulin dependent diabetes with an oral hypoglycemic agent, when possible, along with lifestyle modifications.
OUTCOME Weight loss, discharge
Mr. K is transitioned from aripiprazole to higher-potency oral risperidone, titrated to 6 mg/d. At this dosage, he continues to maintain a delusion about owning a house in Fiji, but was seen responding to internal stimuli less often. The treatment team places him on a diabetic and low-sodium diet of 1,800 kcal/d. His fasting blood glucose levels range in the 70s to 110s mg/dL during his first week of hospitalization.
The treatment team starts Mr. K on oral metformin, titrated to 1,000 mg twice daily, while tapering him off insulin lispro and glargine over the course of hospitalization. The transition from insulin to metformin also is considered because Mr. K’s daily insulin requirement is rather low (<0.5 units/kg).
Mr. K’s course is prolonged because his treatment team initiates the process of conservatorship and placement in the community. Approximately 6 months after his admission, Mr. K is discharged to an unlocked facility with support from an intensive outpatient mental health program. At 6 months follow-up with his outpatient provider, Mr. K’s hemoglobin A1c is 7.0 and he weighs 155 lb with a BMI of 26.5.