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In order to elucidate the tendency to erythrocyte aggregation in gestational diabetes, blood viscosity at a standard hematocrit of 45% (corrected viscosity) was measured at low shear rates in the third trimester of normal pregnancy and pregnancy with gestational diabetes. The mean values (+/- S.D.) for corrected viscosity of 20 gestational diabetic patients were 69.2 +/- 16.6cp at shear rate of 0.11 sec-1, 34.9 +/- 5.3cp at 0.54sec-1 and 27.9 +/- 5.0cp at 0.99sec-1. They were significantly higher than those of 40 normal pregnant patients (55.2 +/- 11.4cp at 0.11sec-1, 29.0 +/- 2.6cp at 0.54sec-1 and 24.4 +/- 2.4cp at 0.99sec-1). The mean value of fibrinogen of gestational diabetic patients was 408.8 +/- 106.7 mg/dl and significantly higher than that of normal patients (313.3 +/- 65.1 mg/dl). The increased tendency to erythrocyte aggregation observed in the diabetic patients was due to increased fibrinogen and would induce microcirculatory disturbance and mild hypoxia in the placental tissue. The cytotrophoblastic cell proliferation which is a characteristic morphological finding of diabetic placenta would be induced as a result of the reaction of placental tissue to the hypoxia thus produced.

Diabetic autonomic neuropathy was expressed quantitatively using the coefficient of variation of R-R intervals (CVR-R) in ECG and its critical level where diabetics were plagued with various symptoms was investigated. The subjects were 58 diabetics under the age of 40 years. ECGs were recorded in the resting supine position and the degree of autonomic neuropathy was expressed as CVR-R by processing 100 consecutive R-R intervals. Symptoms caused by diabetic autonomic neuropathy were determined using a questionnaire. CVR-R were 1.10 +/- 0.34% (mean +/- SD) and 4.31 +/- 2.01% in patients with and without orthostatic hypotension respectively, the former being significantly lower. CVR-R were 1.30 +/- 0.88% and 3.81 +/- 1.31% in those with and without impotence respectively, the former being significantly lower. CVR-R were 0.80 +/- 0.14% and 3.85 +/- 2.17% in those with and without diabetic diarrhea respectively, the former being significantly lower. Concerning sweating abnormality CVR-R were significantly reduced in subjects exhibiting gustatory sweating (1.52 +/- 0.74%) and hypohidrosis (2.26 +/- 1.44%) when compared to those without these symptoms. From the results obtained, a CVR-R of 2% can be considered as the critical level which determines whether symptoms due to diabetic autonomic neuropathy will appear or not.

1. By using the rebreathing method, ventilatory responses to inhaled CO2 were studied in patients with diabetic neuropathy. 2 Their general respiratory functions including vital capacity (VC) and forced expiratory volume in 1 s (FEV 1.0) were within normal ranges and ventilatory responses to CO2 in the range 5.32--5.99 kPa were not significantly different between patients and normal subjects. However, ventilation in the patients was significantly less than that in normal subjects when the alveolar partial pressure of CO2 (PACO2) was above 6.65 kPa. 3. The slope of the CO2 response curves obtained during hyperoxic rebreathing was significantly less in the patients than in the normal subjects. In the patients CO2 response curves with 15% (v/v) O2 were either the same or had lower slopes than those measured with 100% O2. 4. The results suggest that both peripheral and central chemosensitivity, including the activity of the respiratory centre, are reduced in patients with diabetic neuropathy.