Insulin metabolism is altered in migraineurs: A new pathogenic mechanism for migraine?

Background.-Migraine is a complex biochemical dysfunction attributed to a disorder of the trigeminal and hypothalamic pathways. Impairment of glucose metabolism has been reported in migraine, but data are scanty and inconsistent. Objective.-The main aim was to verify whether migraineurs have abnormalities of the glucose and insulin metabolism.We also studied correlations between blood glucose and insulin and between insulin levels and migraine severity. Patients and methods.-Patients with migraine or headache other than migraine, and healthy volunteers were included. All had general blood tests and a standard oral glucose tolerance test after a 12-hour fast, and glucose and insulin were measured. Results.-Over a 6-month period, we recruited 84 migraineurs (73 women, 11 men), 25 patients with nonmigraine headache (20 women, 5 men), and 26 healthy controls (24 women, 2 men). Multivariate analysis confirmed a significant difference between groups for glucose levels (P <.0001), but no significant time interaction. The differences were mostly between migraine and healthy controls (P <.0001) and to a lesser extent between other headaches and healthy controls (P <.05). A significant difference between groups was also found for insulin (P <.0001), with a significant time interaction. The difference was confirmed for migraine compared to other headaches (P <.0001) and healthy controls (P <.0001). Conclusions.-Blood glucose levels may be high in headache patients, but do not seem to be specific to migraineurs. Insulin levels were higher in migraineurs, and seemed specific to this group. These findings are in keeping with recent reports on the effects of insulin on brain functions and lend support to the possibility that insulin is involved in the pathogenesis of migraine.