Consequences of diabetes and pre-diabetes and the role of biochemical parameters of carbohydrate metabolism for the functioning of the prefrontal cortex in obese patients.

Background: The role of executive functions (EF) is to maintain particular behaviours in order to achieve intended goals. EF are crucial in management of pre-diabetes, diabetes and obesity which are grievous diseases and can lead to severe complications. The aims of our study were to: assess EF in group of obese subject with carbohydrate disorders, evaluate whether biochemical factors and comorbidities related to metabolic disorders have adverse effect on EF in this group of patients.

Methods: The study included 185 obese patients (146 women; 39 men) who were divided on three groups: pre-diabetic, diabetic and control subgroup. Patient underwent Wisconsin Card Sorting Test (WCST) to evaluate EF. Assessed biochemical factors included C-peptide, fasting plasma glucose (FPG) and glycosylated hemoglobin A1c (HbA1c).

Results: Diabetic patients showed the worst WCST scores among the rest of groups. Pre-diabetic individuals did not differ in EF performance from control subgroup. We observed significant correlations between FPG and HbA1c and worse WCST scores in pre-diabetic subgroup. In diabetic patients C-peptide correlated with poorer EF. Depressive symptoms and hypertension significantly correlated with non-perseverative errors in WCST.

Conclusions: The subgroup of diabetic patients were the most obese and had the worst glycemia parameters. They also showed the worst EF in WCST. According to obtained results, hyperglycemia positively correlated with poor EF in pre-diabetes. However, in diabetic subjects cognitive deterioration may results from insulin resistance rather than hyperglycemia. In obese individuals with carbohydrate disorders both hypertension and depressive symptoms significantly contributed to EF dysfunction.