We compared various measures of visual-vestibular interaction in subjects with insulin-dependent diabetes mellitus (IDDM) or non-insulin-dependent diabetes mellitus (NIDDM), as well as non-diabetic controls. Subjects with IDDM exhibited significantly greater postural sway than controls on those conditions in the Clinical Test of Sensory Interaction and Balance (CTSIB) which require greater reliance on the vestibular system (p < 0.005). The IDDM group also exhibited significantly worse gaze-holding in darkness and a significantly higher mean slow phase eye velocity (SPV) of optokinetic nystagmus (OKN; p<0.05 for both comparisons). However, there were no significant differences in latency to circularvection (CV). The NIDDM group showed a significant increase in postural sway across all 12 conditions compared with the controls, as well as a significant decrease in gaze-holding in darkness (p < 0.05 and p < 0.0005, respectively). However, they showed no significant difference in OKN SPV and a significant decrease in latency to CV for anticlockwise trials only (p < 0.05). These results suggest that IDDM and NIDDM are both associated with specific but different changes in visual-vestibular interaction.