Left ventricular (LV) function and dimensions were assessed with Doppler and M-mode echocardiography in 26 men and 17 women with newly diagnosed non-insulin-dependent diabetes mellitus, and in 13 healthy control men and 13 women. The diabetic men had lower peak filling rate normalized to mitral stroke volume than the control men (mean +/- standard error of the mean, 4.2 +/- 0.1 vs 4.9 +/- 0.3 stroke volume/s, p less than 0.01). The diabetic women had increased LV mass (102 +/- 12 vs 86 +/- 8 g/m2, p less than 0.01) and decreased fractional shortening (34 +/- 1 vs 38 +/- 1%, p less than 0.05) when compared with control women. At 3 and 15 months, 23 diabetic men and 15 women were reexamined. Concomitantly with decreasing blood glucose levels, fractional shortening improved mainly during the first 3 months and was significantly higher in both diabetic men (36 +/- 2 vs 30 +/- 2%, p less than 0.05) and women (38 +/- 1 vs 34 +/- 1%, p less than 0.05) at 15 months than at baseline. In the diabetic men, peak filling rate increased from 4.3 +/- 0.1 stroke volume/s at baseline to 4.8 +/- 0.2 stroke volume/s at 15 months (p less than 0.05). At 15 months, peak filling rate was correlated (r = 0.61, p less than or equal to 0.001) with autonomic nervous function assessed as heart rate variability during deep breathing test in diabetic men who also showed an inverse correlation between LV hypertrophy and heart rate variability throughout the follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)