Aamodt AH et al. (2007) Headache prevalence related to diabetes mellitus: the Head-HUNT Study. Eur J Neurol 14: 738–744

Diabetes mellitus (DM) could affect the incidence of headache through mechanisms such as altered vascular reactivity and induction of diabetic neuropathy, but studies to date have produced conflicting results. Aamodt and colleagues have now performed a large cross-sectional study in an unselected study population and have demonstrated an inverse relationship between migraine and DM.

The study population comprised 51,249 inhabitants of Nord-Trøndelag county in Norway, aged ≥20 years, who had completed two questionnaires (including questions on DM and headache) as part of the Head-HUNT Study. Diagnosis of DM was validated by blood samples with fasting glucose, antiglutamic acid decarboxylase and C peptide, and headache (defined as headache within the previous year) was confirmed by interview diagnoses.

Multivariate analyses showed a decreased prevalence of migraine in individuals with DM—adjusted prevalence odds ratios (ORs) were 0.4 (95% CI 0.2–0.9) in those with type 1 DM and 0.7 (95% CI 0.5–0.9) in those with type 2 DM, compared with nondiabetic individuals. This relationship held true only for those aged >40 years. In patients with DM, glycated hemoglobin level >6.6% was further associated with reduced prevalence of migraine. In addition, DM duration ≥13 years was associated with a reduced OR for all headache types (0.6, 95% CI 0.4–0.9; compared with DM duration ≤3 years). There were no obvious associations between DM and nonmigrainous headache or between headache frequency and DM.

The reasons for these results remain unexplained, but the authors believe that DM could induce pathophysiological changes that help protect against migraine.