Our objective was to investigate the relationship between gastric emptying and mesenteric blood flow in type 1 diabetic patients with (CAN+) and without (CAN-) cardiac autonomic neuropathy. CAN was determined by a series of cardiovascular reflex tests and power spectral analysis of heart rate variations (HRV) using a computerized system. We calculated from these data a score for cardiac autonomic neuropathy with a maximum of 7 points (1 point for abnormal value of: CV of HRV at supine rest, CV of HRV during deep breathing, Valsalva ratio, lying-to-standing ratio, PSA of HRV in the low frequency band, PSA of HRV in the mid frequency band, blood pressure response to standing). Patients were considered to have CAN if at least 3 of the 7 parameters were found to be abnormal (CAN score > or = 3). The resulting groups (CAN-, n = 14 vs. CAN+, n = 16) were well matched with respect to age (53 +/- 11 vs. 51 +/- 12 years), BMI (27.2 +/- 3.3 vs. 25.9 +/- 3.6 kg/m2), duration of diabetes (162 +/- 157 vs. 158 +/- 100 months), fasting blood glucose (6.9 +/- 2.6 vs. 6.8 +/- 2.4 mmol/l) and HbA1c (7.2 +/- 1.5 vs. 7.3 +/- 2.0%). Gastric emptying was determined by real-time ultrasonography (antral planimetry) during 60 min after a semiliquid test meal (Fresubin diabetes 300 ml, 53% carbohydrate, 32% lipid, 15% protein) and the blood flow of the superior mesenteric artery was measured by Doppler ultrasound technique. Type I diabetic patients with CAN had a significantly higher CAN score than those without CAN (6.1 +/- 0.4 vs. 1.3 +/- 0.7). Mean preprandial (before ingestion of the test meal) as well as postprandial (immediately after ingestion of test meal) antral areas of CAN+ (5.2 +/- 2.0v/10.9 +/- 2.8 cm2) and CAN- (5.1 +/- 1.5/10.8 +/- 2.2 cm2) were comparable. CAN+ had significantly slower decrease of postprandial antral areas at 15, 30, 45 and 60 min after ingestion of test meal (-1.7 +/- 0.4/-8.3 +/- 1.2/-9.5 +/- 0.9/-19.5 +/- 2.0 delta % compared to postprandial value) compared to CAN- (-8.9 +/- 1.8/-22.5 +/- 2.6/-29.1 +/- 2.9/-35.5 +/- 2.9 delta %). The increase in mesenteric blood flow at 15, 30 and 45 min after the meal was significantly reduced in CAN+ compared to CAN- patients. Significantly negative correlations were found between the CAN score and the decrease of antral area as well as between CAN score and the increase of diastolic mesenteric blood flow and significantly positive correlations between the decrease of antral area and the increase of diastolic mesenteric blood flow. In conclusion, type 1 diabetic patients with cardiac autonomic neuropathy showed delayed gastric emptying and diminished mesenteric blood flow during 60 min after ingestion of a semiliquid test meal.