We investigated the relationship between asymptomatic multiple lacunae (ASML) and related risk factors by using brain MRI in 209 patients including 152 NIDDM patients. Patients with ASML (97 cases) were significantly older (68 +/- 9 vs. 63 +/- 10) and hypertension was more frequent (57/97 vs. 33/112) than in patients without ASML. In addition, by multivariate analysis, ASML showed significant association with aging and hypertension, but not with NIDDM. In the NIDDM patients, diabetics with ASML were significantly older, and showed a higher association with hypertension and triopathy than those without ASML, although the results were the same for the middle-aged (< 65 years old) diabetics. From multivariate analysis, the lesions in the penetrating branch area were highly associated with hypertension (F = 8.46) and nephropathy (F = 4.75), while those in the subcortex and white matter were associated with aging (F = 6.02) and retinopathy (F = 5.15). In the middle-aged diabetics, the former was associated with hypertension (F = 10.72) and retinopathy (F = 13.32), whereas the latter was associated with retinopathy (F = 20.76). In the elderly diabetics, no significant association was found in either lesions. These results suggest that control of hypertension and prevention of microangiopathy by keeping good control of blood glucose, is essential to prevent asymptomatic lacunae in NIDDM patients.