Aims: To test the effect of repetitive active transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex (DLPFC) associated with a hypocaloric diet (HD) on glucose homeostasis in overweight or obese adults.
Method: We selected in a RCT double-blind study, overweight or obese adults with different degrees of glucose tolerance to complete a 4-week (20 sessions; five consecutive weekdays) of fixed-dose tDCS (2mA, 20min) delivered over the right DLPFC associated with a standard HD. Subjects were randomly assigned (1:1) and stratified by sex to active tDCS group (AG) or sham tDCS group (SG). Changes on the glycemic and insulinemic response were assessed in a 4h liquid meal tolerance test (LMTT), performed before (t0) and after (t20) the 4-week intervention. Plasma glucose and insulin concentrations were used to determine glucose and insulin AUCs, indices of insulin sensitivity (MISI, Matsuda Insulin Sensitivity Index), insulin secretion (ISI, Insulin Secretion Index), and pancreatic β-cell function (DI, Disposition Index). Data were analyzed with generalized estimating equations adjusted for age, carbohydrate intake, and weight loss (%).
Results: Twenty-eight participants were randomized (79% obese; 29% IGT, 4% T2D; 37.6 [5.8] years). Changes over the time (mean [95% CI]) for FPG was higher in AG than in SG (∆t20-t0 = −7.8 [−14.0, −1.6] vs. ∆t20-t0 = −0.9 [−4.0, 2.1] mg/dL; p = 0.043) after the intervention. Likewise, the MISI was improved in AG compared with SG (∆t20-t0 = 3.2 [1.5 to 4.9] vs. ∆t20-t0 = 0.5 [−1.5, 2.5] pmol-1x mmol-1; p = 0.044). There were no significant differences between groups in fasting insulin, glucose and insulin AUCs, ISI, or DI over the study.
Conclusions: Repetitive active tDCS over the right DLPFC may be a promising non-invasive technique that could be used to improve glucose homeostasis in overweight or obese individuals on a low-calorie diet. ClinicalTrials.org: NCT02683902.
C. de Araujo: None. R.C. Fitz: None. G.R. Natividade: None. A.F. Osório: None. P.N. Merello: None. P. Schestatsky: None. F. Gerchman: Speaker's Bureau; Self; Novo Nordisk Inc. Other Relationship; Self; Sanofi-Aventis.
Hospital de Clínicas de Porto Alegre (FIPE15-0119, 16-0417)