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Abnormal insulin levels found in first-episode schizophrenia

Recent findings indicated impaired insulin/glucose homeostasis in drug-naïve individuals with first-episode schizophrenia.

“Before the introduction of antipsychotics, links between schizophrenia and abnormal glucose metabolism levels were found in the late 1800s as an increased prevalence of diabetes in families with a history of ‘insanity,’” Johann Steiner, MD, PhD, of University of Magdeburg, Germany, and colleagues wrote. “Furthermore, it is known that some patients with psychosis require higher dosages than other patients when applying insulin therapy, suggestive of insulin resistance.”

To determine if insulin resistance in schizophrenia can be distinguished from stress-related and medication effects, researchers evaluated homeostatic model assessment of insulin resistance (HOMA-IR) and stress hormone levels among 24 drug-naïve individuals with first-episode schizophrenia and 24 controls. Urine and blood samples were obtained in the morning after participants fasted.

HOMA-IR was twice as high among participants with schizophrenia (median IQR = 0.72; 95% CI, 0.38-2.28), compared with controls (median IQR = 0.36; 95% 0.26-0.84; P = .02).

Serum cortisol levels increased 1.4-fold, with a median IQR of 26.65 (95% CI, 17.78-40.3; P = .04).

Urinary metanephrine (median IQR = 71.5; 95% CI, 42.9-127.1; P = .03) increased approximately 1.7-fold and normetanephrine (median IQR = 147.7; 95% CI, 89.1-217.7; P = .08) levels increased approximately 1.5-fold.

HOMA-IR was associated with BMI (P = .001), but was not significantly associated with cortisol, metanephrine, normetanephrine, or smoking levels.

HOMA-IR was not associated with Positive and Negative Syndrome Scale scores.

Additional testing indicated schizophrenia-related increases in HOMA-IR among non-smokers (P = .02).

Analysis of covariance using an aligned rank transformation confirmed diagnostic group differences in HOMA-IR (P = .003). however, only BMI significantly influenced this model (P = .005).

“These results support the recently raised notion of impaired insulin/glucose homeostasis in drug-naïve patients with first-episode schizophrenia, small sample and effect sizes notwithstanding,” the researchers wrote. “Reduced insulin sensitivity may arise independently from pharmacotherapy, hormonal stress axis activation, or obesity. Glucose metabolism levels should be assessed in larger samples and other psychiatric disorders to examine specificity for schizophrenia.” – by Amanda Oldt

Disclosure: Steiner reports no relevant financial disclosures. Please see the study for a full list of relevant financial disclosures.