Aim of this study was to investigate a) if through Magnetic Resonance Imaging (MRI) it was possible to reveal cerebral alterations in patients with insulin-dependent diabetes mellitus (IDDM); b) if there was any correlation with hypoglycemic episodes, glycometabolic control, microvascular alterations and diabetic peripheral neuropathy. For this purpose ten ID-DM patients under treatment with human insulin, aged 19-30 yr with the disease, the duration being from 1 to 19 yr, were investigated by MRI using a Philips Gyroscan. Spin Echo sequences were used with images in T1 T2 in sagittal and axial planes. To measure the ventricular dilatation the cerebroventricular index (CVI) was evaluated. The MRI has put in evidence in 7/10 patients a dilatation in the lateral ventricles and subarachnoidal spaces of the cerebral vault and the cerebellum clearly due to cerebral atrophy. The CVI mean values (34.78 +/- 2.92) were statistically (p < 0.001) higher in diabetic patients respect to control subjects (CVI mean values 27.5 +/- 1.58). These alterations did not present clear correlations with the degree of glycometabolic control, duration of disease, number of symptomatic hypoglycemic episodes and threshold for hypoglycemic symptoms, retinal microvascular alterations, microalbuminuria, diabetic peripheral neuropathy. The clinical or functional relevance of CVI changes and the exact pathogenic mechanism remains to be clarified.