1822-P: Transient Insulin Deprivation Alters Cognition and Brain Energy Metabolism in People with Type 1 Diabetes

Introduction: Diabetes is associated with impaired cognition but the effect of the transient insulin deprivation on cognition and its underlying mechanisms remain unclear.

Objective: We determined whether transient insulin deprivation in type 1 diabetic adults (T1D) and adolescents alters brain structure, functions and blood flow compared to nondiabetics (ND).

Methods: We performed structural MRI, phosphorous³¹ NMR spectroscopy, and neuropsychiatric testing at baseline and following 6 hours of insulin deprivation in 14 adolescent (14-17 years) and adult (18-44 years) T1D and age- sex- and BMI-matched ND controls.

Results: There were no significant changes on baseline structural MRI between the groups. After insulin deprivation, T1D had a significantly greater blood glucose (272 vs. 85 mg/dL), greater beta hydroxybutyrate (1.45 vs. 0.3 mmol/L), and decreased bicarbonate level (25.5 vs. 21.5 mmol/L) at six hours compared to ND. Following insulin deprivation, there was a significant difference in T1D left cortical volume compared to ND. On diffusion tensor imaging at baseline and after insulin deprivation, T1D had a higher fractional anisotropy compared to ND. T1D also had a significant decline in phosphocreatine/ATP after insulin deprivation compared to ND. Lastly after insulin deprivation, T1D failed to have learned improvement on repeat neuropsychiatric testing, with ND having significantly greater improvements in executive function, attention and working memory compared to T1D.

Conclusion: Transient hyperglycemia and insulin deprivation caused a significant decline in some important aspects of cognition and brain energy metabolism, indicating that even transient insulin deprivation affects brain function and morphology. This may have important clinical implications as many diabetic patients inadvertently have occasional periods of transient insulin deprivation.