Plasma Insulin Level Correlation to Metabolic Parameter Shifts in Hospitalized Psychiatric Patients.

Objective: To identify potential correlations between baseline plasma insulin level and shifts in metabolic status in psychiatric inpatients.

Methods: A population of 75 patients was identified for this single-center, retrospective study conducted at a state psychiatric hospital in Kansas City, Missouri. Patients were selected on the basis of presence of a baseline fasting plasma insulin level drawn at admission; duration of stay ≥ 12 weeks between August 1, 2013, and December 31, 2015; and presence of metabolic laboratory and weight measurements at baseline and 3 months. Total initial plasma insulin level (≥ 19 µIU/mL or < 19 µIU/mL) was compared to shifts in metabolic laboratory measurements and weight. A secondary analysis was performed to detect association between the numerical values of assessed parameters and the numerical values for plasma insulin measurements.

Results: The primary analysis found no correlation between plasma insulin level and changes in any metabolic parameter category at 3 (n = 75) or 6 months (n = 30) after admission. Secondary analysis found significant correlations between the numerical values of baseline total plasma insulin level and fasting plasma glucose level at baseline (r = 0.492, P < .001), 3 months (r = 0.247, P = .035), and 6 months (r = 0.723, P < .001). Secondary analysis demonstrated a significant correlation between baseline total plasma insulin level and hemoglobin A1c values at baseline (r = 0.329, P = .004), 3 months (r = 0.455, P < .001), and 6 months (r = 0.517, P = .003).

Conclusions: Baseline total plasma insulin levels were strongly correlated with parameters affected directly by alterations in glucose up to 6 months after admission but were weakly correlated or not correlated with other metabolic parameters. The results do not support routine use of plasma insulin as a predictor for shifts in metabolic parameters in patients receiving antipsychotic medications.