Objective: To determine whether systematic evaluation of cognitive function by the Mini-Mental State Examination (MMSE) allows the objective detection and documentation of cognitive deterioration in patients referred for evaluation of suspected hypoglycaemic disorders by the 72-h fast.
Design: Prospective case series.
Methods: In 50 patients referred for evaluation of suspected hypoglycaemic disorders, the MMSE score (maximum 30 points) was assessed at the start and at the end of the fast.
Results: The fast was terminated before 72 h in 14 patients because they developed neuroglycopenic symptoms due to hypoglycaemic disorders. Their MMSE score fell from a median of 29 points (range 20-30) at the beginning to 17 points (range 0-24) at the termination of the fast. The score dropped by > or =6 points in all patients with hypoglycaemic disorders. Median (range) plasma glucose concentration at the end of the fast was 2.1 (1.1-2.5) mmol/l. Thirty-six individuals developed no neuroglycopenic symptoms throughout the 72-h fast, their MMSE score remained between 27 and 30 throughout the fast and their median plasma glucose concentration dropped to 2.9 (2-3.6) mmol/l.
Conclusions: Systematic evaluation of cognitive function by the MMSE at the beginning and at the termination of the fast allows objective determination and documentation of the deterioration of the cognitive state in patients with hypoglycaemic disorders. A decline in the cognitive performance by > or =6 points in the MMSE score rather than a distinct plasma glucose concentration should be used as the criterion to terminate the prolonged fast before 72 h.