Hyperamylasemia, specific pancreatic enzymes, and hypoxanthine during recovery from diabetic ketoacidosis

The contribution of the exocrine pancreas to hyperamylasemia in diabetic ketoacidosis was investigated by measuring total amylase, salivary and pancreatic isoamylases, cathodic trypsin-like immunoreactivity, and pancreatic lipase in 12 consecutive patients recovering from diabetic ketoacidosis. Hyperamylasemia was present in six of the patients [50%; expected incidence: 21.1-78.9% (95% confidence limits)]--in five with simultaneously increased activities of all three specific pancreatic enzymes, and in one with only increased salivary isoamylase. The serum concentration of hypoxanthine--an indicator of the cellular energy state--was above normal in all patients at admission. We found no differences in concentrations of hypoxanthine in serum of patients with or without hyperamylasemia or in patients with or without increases in the specific pancreatic enzymes. In none of the patients was the clinical course or the time--concentration curves of the pancreatic enzymes consistent with acute pancreatitis. The pathogenic mechanism leading to hyperamylasemia in diabetic ketoacidosis remains uncertain.

Proximal glomerulo-tubular balance in patients with type 1 (insulin-dependent) diabetes mellitus

To evaluate the glomerulo-tubular balance of sodium and water in the proximal tubules of diabetic patients with elevated glomerular filtration rate, the renal plasma clearance of lithium and the glomerular filtration rate (51Cr-EDTA plasma clearance) were determined simultaneously in 11 ambulatory Type 1 (insulin-dependent) diabetic patients (aged 25-35 years) with no evidence of diabetic nephropathy and in 10 age-matched healthy subjects. The renal plasma clearance of lithium, which is a measure of flow from the proximal tubule into the thin descending limb of the loop of Henle, did not differ between diabetic and control subjects (28.9 +/- 4.0 versus 28.3 +/- 5.1 ml/min per 1.73 m2 surface area, mean +/- SD), whereas the glomerular filtration rate in the diabetic patients was significantly higher than in the control subjects (136 +/- 10.2 versus 108 +/- 13.6 ml/min per 1.73 m2, p less than 0.001). The same held true for the fractional reabsorption rate in the proximal tubules (78.7 +/- 3.2 versus 73.6 +/- 4.9%, p less than 0.02). The results indicate that the elevation of the glomerular filtration rate in diabetic patients is associated with a parallel increase in the proximal reabsorption rate. This type of glomerulo-tubular balance implies that the flow of water and flux of sodium to the segments distal to the proximal tubule are kept constant during variations in the glomerular filtration rate.

The measurement of hemoglobin A1. Evaluation of an 'aldimine eliminator'

The efficiency of a newly introduced 'hemoglobin A1 aldimine eliminator' in minimizing the effect of recent fluxes of glucose on the determination of total glycosylated hemoglobin (HbA1) was evaluated by comparing HbA1 values measured during morning fast and again 6 h postprandially in 26 insulin-dependent diabetic subjects by Isolab's Fast Hemoglobin Test System employing dialyzed and aldimine eliminator-added non-dialyzed hemolysate. The HbA1 values determined by this microcolumn procedure were also compared with those of the conventional macrocolumn method of Trivelli. HbA1 measured by the microcolumn procedure and aldimine eliminator using non-dialyzed hemolysates did not differ from the HbA1 values based on dialyzed hemolysates, and a good correlation was found between the macrocolumn method and the Isolab's Fast Hemoglobin Test System employing both aldimine eliminator added non-dialyzed hemolysate (r = 0.88, p less than 0.001) and dialyzed hemolysate (r = 0.97, p less than 0.001). When 6 h changes were assessed, the mean blood glucose had increased from 11.7 to 15.5 mmol/l (p less than 0.001), and no significant increase in HbA1 occurred when HbA1 was assayed in aldimine eliminator-added non-dialyzed hemolysates (mean fast HbA1: 11.7% and mean postprandial HbA1: 11.8%). Therefore, the use of the HbA1 aldimine eliminator appears to be valuable, practical and time-saving.

Glomerular hyperfiltration and blood viscosity in type I (insulin-dependent) diabetic subjects

To investigate whether the increased glomerular filtration rate (GFR) in short-term diabetic patients is related to increased blood- or plasma viscosities, GFR [( 51Cr] EDTA-clearance), whole blood- and plasma viscosities were simultaneously determined in 16 insulin-dependent diabetic subjects, aged 11 to 34 years (duration of disease 0.1 to 8 years) and compared to the results in healthy subjects. Mean standard GFR +/- SD (that is, GFR corrected to body surface area of 1.73 m2) was significantly higher in the diabetics than in 16 age- and sex matched controls (142 +/- 26 ml/min vs. 123 +/- 18 ml/min, P less than 0.02). Blood viscosities at different shear rates and the plasma viscosity were not significantly different in the two groupes , although the plasma fibrinogen level was significantly elevated in the diabetics (376 +/- 60 mg%, vs. 289 +/- 37 mg%, P less than 0.001). No correlation was found between GFR and the viscosity measurements. The results of the present study do not support the suggestion that the increased GFR in short-term diabetics is related to changes in blood viscosity.

Effect of smoking on red cell oxygen transport and release in diabetic pregnancy

In order to investigate the effect of smoking on the red cell oxygen transport and release in pregnant diabetic women, 23 smokers and 23 non-smokers were studied in the third trimester. The two groups were comparable with regard to blood glucose regulation, as the median concentration of blood glucose and glycosylated hemoglobin (Hb A1c) did not differ. Red cell 2, 3-diphosphoglycerate (2, 3-DPG) levels were significantly lower in the smokers than in the non-smokers (16.5 vs 17.8 mumol/gHb, p less than 0.01). P50 of the oxyhemoglobin dissociation curve at actual pH and at pH 7.40 was also significantly lower in the smokers (25.9 vs 26.9 mmHg, p less than 0.01, and 26.5 vs 27.8 mmHg, p less than 0.01 respectively). Red cell 2, 3-DPG was significantly correlated with P50 at pH 7.40 (r = 0.73, p less than 0.001). Arterial oxygen saturation was reduced to the same degree in smokers and in non-smokers, as compared with healthy non-smoking pregnant women and no adaptive increase in the hemoglobin concentration occurred in the pregnant diabetic smokers. The study suggests that smoking in pregnant diabetic women impairs the adaptive increase in 2, 3-DPG associated with diabetes-induced hypoxia.

Blood-oxygen transport in first trimester of diabetic pregnancy

Factors involved in blood-oxygen transport were studied in 46 pregnant women during the first trimester. All had type 1 (insulin-dependent) diabetes and comparisons were made with similar measurements from 19 non-diabetic pregnant women, also in the first trimester. The concentration of hemoglobin A1c (HbA1c) was significantly increased (7.6% versus 4.4%, p less than 0.01) and arterial oxygen saturation was decreased (0.95 versus 0.98 mol/mol, p less than 0.01) in the pregnant diabetics compared with the non-diabetics. The hemoglobin concentration was significantly elevated in the diabetic women (12.9 versus 12.1 g/100 ml, p less than 0.01). Even though the red cell 2,3-diphosphoglycerate content was the same in the two groups, and pH was significantly lower in the diabetic women, hemoglobin-oxygen affinity was slightly increased in the diabetic patients (P50 at actual pH: 26.2 versus 26.7 mmHg, p less than 0.05; P50 at pH 7.40: 27.0 versus 28.0 mmHg, p less than 0.01). The study has demonstrated certain modifications in the blood oxygen transport system in the first trimester of pregnancy of diabetic women that are possibly related to the presence of excess amounts of glycosylated hemoglobin with increased oxygen affinity. This disturbance in maternal oxygen transport, particularly when associated with diabetic vascular disease, may lead to episodes of fetal hypoxia. Such fetal hypoxia may be a pathogenetic factor for the development of congenital malformations in the outcome of diabetic pregnancy.

Red cell 2,3-diphosphoglycerate and hemoglobin--oxygen affinity during normal pregnancy

The concentration of red cell 2,3-diphosphoglycerate (2,3-DPG), hemoglobin-oxygen affinity and other oxygen transport variables were determined during first, second and third trimester of normal pregnancy as well as 3 months post partum in 18 healthy women. The median concentration of red cell 2,3-DPG increased significantly from the first to the third trimester (16.1 to 17.0 mumol/gHb, p less than 0.01), whereas 2,3-DPG decreased significantly post partum (p less than 0.01). Normal pregnancy was also associated with relative anemia, a significant increase in arterial pH, hypocapnia and hypophosphatemia. The difference in hemoglobin concentration from the first trimester to 3 months post partum was correlated inversely with the difference in red cell 2,3-DPG content (r = -0.52, p less than 0.05). In spite of the variations in red cell 2,3-DPG, hemoglobin-oxygen affinity expressed as P50 at actual pH remained unchanged during pregnancy and post partum. The study suggests that the increased level of 2,3-DPG during pregnancy may in part represent compensation for physiologic anemia and also compensate for a factor leading to increased hemoglobin-oxygen affinity during pregnancy.

Serum amylase during recovery from diabetic ketoacidosis

To elucidate the mechanism of the hyperamylasaemia which is often found in diabetic ketoacidosis, 9 patients who were admitted in this disease state were studied. Blood samples were taken every 4 hours for the first 24 hours and thereafter daily for 7 days. Serum amylase concentration increased gradually in all patients, from 256 (65-1155) U/1 at the initial sampling to a maximum of 1160 (210-2670) U/1 20-24 hours later (p. greater than 0.01), median values with 95% confidence limits. Simultaneously, plasma inorganic phosphate concentrations decreased from a median value of 1.35 mmol/l to 0.45 mmol/l (p less than 0.01), and a significant negative correlation was found between the changes in these parameters in 5 patients. Isoenzyme analysis in 8 of the patients showed that hyperamylasaemia was of the "salivary type" in two and of the "pancreatic type" in two. None of the patients had clinical signs of pancreatitis. It is concluded that in diabetic ketoacidosis, the increase in serum amylase concentration observed in all patients is closely related to the action of insulin in the majority of these, and some possible mechanisms are discussed.

Red cell 2,3-diphosphoglycerate and hemoglobin-oxygen affinity during diabetic pregnancy

Factors involved in blood oxygen transport were measured serially in the first, second and third trimester of pregnancy in 23 insulin-dependent diabetic women. Twenty-six non-pregnant diabetic patients served as a reference group. Diabetic pregnancy was associated with relative anemia, a significant increase in arterial pH, and hypocapnia. The concentration of red cell 2,3-diphosphoglycerate was significantly higher in the first trimester of diabetic pregnancy compared with non-pregnant diabetics (median value 16.4 vs. 15.0 mumol/g hemoglobin, p less than 0.02) and increased gradually from the first to the third trimester (16.4 to 17.2 mumol/g hemoglobin, p less than 0.01). The hemoglobin A1c concentration decreased simultaneously from 8.1% to 7.3% (p less than 0.01). The level of hemoglobin A1c in the first trimester was significantly lower than that in the non-pregnant diabetic patients (8.1 vs. 9.3%, p less than 0.01). In spite of the increase in red cell 2,3-diphosphoglycerate content and the decrease in hemoglobin A1c, factors known to reduce hemoglobin-oxygen affinity, the position of the oxyhemoglobin dissociation curve remained unchanged during diabetic pregnancy: P50 at actual pH in the first trimester, was 26.0 mmHg; in the second trimester, 26.9 mmHg, and in the third trimester, 26.8 mmHg (NS). These values of P50 at actual pH were identical with the value in the non-pregnant group (26.6 mmHg). Other factors influencing hemoglobin-oxygen affinity, such as hemoglobin concentration, hydrogen ion concentration and arterial oxygen saturation remained unchanged during diabetic pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Diabetic oxygen-hemoglobin equilibrium curves evaluated by nonlinear regression of the Hill equation

The oxygen-hemoglobin equilibrium curves ( OHECs ) were measured on whole blood samples from 131 individuals (33 normal and 26 diabetic adults and 30 normal and 42 diabetic juveniles) using a Radiometer Dissociation Curve Analyzer (DCA-1). All measurements were made in the morning following an overnight fast and without exogenous insulin. The saturation versus Po2 data were fitted to the Hill equation using a previously described nonlinear regression algorithm to yield the parameters describing the position (P50) and shape (n) of each OHEC . It was found that the Hill model could be used to describe OHECs of both normal and diabetic subjects. A small (approximately 10%) but significant decrease in P50 was found for the diabetic juveniles compared to normal juveniles. There appeared to be no change in P50 with diabetes in adults. However, in these diabetic subjects, the P50 had been increased by the somewhat elevated levels of 2,3-DPG. No difference in n was found between either group of diabetics and their corresponding group of normals but n was approximately 5% lower in juveniles than in adults. The ability of blood to release oxygen to tissue may be transiently impaired in diabetic juveniles because of the left shift of their OHECs .

Tubular reabsorption rates as related to elevated glomerular filtration in diabetic children

To study renal tubular reabsorption and tubulo-glomerular balance in diabetic children, glomerular filtration rate (GFR) and tubular reabsorption rates of sodium, glucose, ultrafilterable calcium, and phosphate were measured during fasting in 26 ambulatory type I (insulin-dependent) diabetic children without clinical signs of microangiopathy (age 7-14 yr; duration of diabetes 3-14 yr). Similar measurements were made in 28 healthy school children (age 8-14 yr). Mean GFR in the diabetic children was significantly higher than in the normal children (138 versus 109 ml/min/1.73 m2, P less than 0.01). Mean tubular reabsorption rates of sodium, glucose, and calcium were significantly increased in the diabetic subjects (P less than 0.001). In contrast, tubular reabsorption rate of phosphate in the diabetic subjects was not enhanced. The renal threshold concentration of phosphate (TmPO4/GFR) was suppressed in the diabetic compared with the healthy subjects (1.23 versus 1.73 mmol/L, P less than 0.001). TmPO4/GFR was unrelated to circulating parathyroid and growth hormone concentrations but correlated inversely with the reabsorption rate of glucose (r = -0.53, P less than 0.01). Sodium reabsorption was closely correlated to GFR in both diabetic (r = 0.99, P less than 0.0001) and healthy subjects (r = 1.00, P less than 0.0001), and both groups showed identical regression lines. The tubular glucose reabsorption rate was independent of GFR in the diabetics. Tubular calcium and phosphate reabsorptions correlated equally well with sodium reabsorption and with GFR in the diabetic and healthy subjects (P less than 0.001). The maximal reabsorption of phosphate relative to GFR was lowered in the diabetic children.(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation of serum unconjugated oestriol to red cell 2,3-diphosphoglycerate levels in diabetic pregnancy

In order to evaluate the possible underlying factors for the increase in red cell 2,3-diphosphoglycerate content observed in late diabetic pregnancy, its relationship with serum unconjugated oestriol, human placental lactogen, haemoglobin and hydrogen ion concentrations was investigated in 42 pregnant diabetic women. A significant correlation was found between red cell 2,3-diphosphoglycerate and serum unconjugated oestriol (r = 0.54, p less than 0.001), whereas no correlation was present between 2,3-diphosphoglycerate and the following variables: arterial pH, haemoglobin concentration and human placental lactogen. The content of 2,3-diphosphoglycerate correlated significantly with haemoglobin-oxygen affinity expressed as P50 at pH 7.4 (r = 0.34, p less than 0.05). The results of this study indicate that serum unconjugated oestriol may participate in the regulation of red cell 2,3-diphosphoglycerate content and thereby of the maternal blood oxygen release to the fetus.

Characterization of oxygen-hemoglobin equilibrium curves using nonlinear regression of the Hill equation: parameter values for normal human adults

Measurements of oxygen concentration versus PO2 in blood from 33 normal adults were fitted, using a special nonlinear regression analysis, to the Hill equation to obtain the parameters describing the position (P50) and shape (n) of each oxygen-hemoglobin equilibrium curve (OHEC). Data between 20% and 97% saturation were described well by this empirical two-parameter model. The mean (+/- SD) P50 and n were found to be 26.2 (+/- 0.8) torr and 2.50 (+/- 0.07), respectively, in good agreement with previously published values. Some normal individuals, however, deviated markedly from the averages indicating that the published values cannot be applied to everyone.

Dysfunction of tubular phosphate reabsorption related to glomerular filtration and blood glucose control in diabetic children

The renal handling of inorganic phosphate was studied by measuring the urinary excretion rate of phosphate (UPO4V), phosphate-(Cr51) EDTA clearance ratio (CPO4/GFR) and maximal tubular reabsorption of phosphate per litre glomerular filtrate (TmPO4/GFR) during fasting in 26 ambulatory Type 1 (insulin-dependent) diabetic children without clinical signs of microangiopathy (age: 7-14 years; duration of disease: 3-14 years). Similar measurements were made in 28 healthy schoolchildren (age: 8-14 years). UPO4 V and CPO4/GFR were significantly enhanced in the diabetic children (p less than 0.001) and correlated with the degree of hyperglycaemia (p less than 0.005). TmPO4/GFR was significantly suppressed in the diabetic children (1.23 versus 1.73 mmol/l, p less than 0.001). This disturbance was neither related to changes in serum parathyroid hormone nor to growth hormone concentrations but was inversely correlated with the degree of hyperglycaemia (r = -0.61, p less than 0.001) and with tubular reabsorption of glucose (r = -0.53, p less than 0.01). In spite of the markedly lowered TmPO4/GFR in the diabetic subjects, the mean maximal (TmPO4) and absolute tubular phosphate reabsorption rates were equal to those of the 28 healthy subjects. Both in the diabetic and healthy subjects, these parameters were positively correlated with glomerular filtration rate which was significantly elevated in the diabetic children (138 versus 109 ml/min per 1.73 m2, p less than 0.01). The study demonstrates a dysfunction in tubular phosphate reabsorption in diabetic children which is related to glycaemic regulation.

The effect of etidronate disodium (EHDP) on retinopathy in insulin-dependent diabetic patients

In a randomized double-blind study the effect of etidronate disodium (EHDP) on retinopathy, plasma inorganic phosphate and blood oxygen transport was assessed in 26 insulin-dependent diabetic patients. Following 6 months of EHDP administration, plasma inorganic phosphate had increased significantly (1.48 vs 1.14 mmol/l; P less than 0.01). Red cell, 2,3-diphosphoglycerate concentration (16.9 vs 15.1 mumol/g Hb; P less than 0.01) and the haemoglobin-oxygen affinity measured by pO2 at 50% oxygen saturation (P50) had also increased significantly (27.5 vs 26.3 mmHg; P less than 0.01). No changes had occurred in mean blood glucose and haemoglobin A1c concentrations, indicating a comparable degree of glucose regulation. Following 6 months of EHDP administration an association was found between improvement in retinopathy and the increase in plasma inorganic phosphate.

Changes in red blood cell oxygen transport in diabetic pregnancy

Parameters of red cell oxygen transport were studied in 23 nonsmoking, insulin-dependent diabetic women and 20 nonsmoking healthy women late during pregnancy. In the pregnant diabetic women, arterial oxygen saturation (SAT) and arterial oxygen tension were significantly decreased. SAT correlated inversely with hemoglobin Alc (Hb Alc) (diabetic women: r = -0.43, p less than 0.05; total material: r = 0.66, p less than 0.001). Red blood cell 2,3-diphosphoglycerate (2,3-DPG) was significantly increased in the pregnant diabetic women (p less than 0.01), but the 2,3-DPG-induced change in hemoglobin-oxygen affinity was impaired. P50 (oxygen affinity, i.e., Po2 at 50% oxygen saturation) at actual pH correlated inversely with Hb Alc of the diabetic women (r = -0.45, p less than 0.05). The suggestion is made that, in diabetic pregnancy, particularly in poorly regulated cases, fetal hypoxia may be an important factor of the increased risk of intrauterine fetal death.

Increased insulin receptor binding to monocytes from insulin-dependent diabetic patients after a low-fat, high-starch, high-fiber diet

To determine if the insulin sparing effect of a low-fat, high-starch, and high-fiber diet might be mediated through changes of cellular insulin receptor binding, we have in a clinically controlled diet study examined insulin receptors on erythrocytes and monocytes from 40 patients with insulin-dependent diabetes meilitus. Twenty diabetic subjects were treated with a weight-maintaining, low-fat, high-starch, and highfiber diet for 4 wk (alternative diet group) while a comparable group of another 20 diabetic subjects was treated with a conventional high-fat, low-carbohydrate diet (control diet group). In the alternative diet group the intake of starch increased by 56% (P < 0.001) with unchanged intake of simple carbohydrates, the intake of indigestible carbohydrates (fibers) increased by 90% (P < 0.001), the intake of saturated fat was reduced by 32% (P < 0.01) with unchanged intake of polyunsaturated fat, and the cholesterol consumption decreased by 39% (P < 0.01). Food intake remained constant in the control diet group. During the first 2 wk after change of diet the patients in the alternative diet group had frequent clinical signs of increased insulin sensitivity (hypoglycemia) demanding significant reductions (about 25%) of insulin requirement (P < 0.005 after week 1 and P < 0.001 after weeks 2-4). In the same group of diabetic subjects insulin binding to monocytes at insulin tracer concentration increased 25% (P < 0.05) after week 2 and 34% (P < 0.01) after week 4. In contrast insulin receptors on erythrocytes were unchanged. Moreover, significant reductions were shown in fasting plasma concentrations of free insulin (P < 0.02 after weeks 3 and 4) and ketone bodies (P < 0.05 after week 3 and P < 0.01 after week 4), and fasting serum concentration of total cholesterol (P < 0.001 after weeks 2 and 4). No significant changes occurred in the alternative diet group in the following quantities: fasting plasma and 24-h urine glucose concentrations, percentage of glycosylated hemoglobin, fasting plasma concentrations of FFA, or fasting serum concentration of triglyceride. No significant changes in any of the measured variables were found in the control diet group. We conclude that the insulin sparing effect of a low-fat, high-starch, high-fiber diet in insulin-dependent diabetic subjects may be partly mediated through an increased insulin binding. Improved metabolic control was obtained as judged by the significant fall of the plasma concentration of ketone bodies while glycemia and glucosuria were unchanged.

Glomerular filtration rate and extracellular fluid volume in insulin-dependent patients with diabetes mellitus

To investigate whether the increased GFR in diabetic patients is related t an increased ECV, GFR ([51Cr] EDTA clearance) and ECV (distribution volume of [51Cr] EDTA) was determined in 26 insulin-dependent diabetic men aged 17 to 50 years (duration of disease 0.1 to 14 years) and compared to the results in normal men. Mean standard GFR +/- SD (that is, GFR corrected to a body surface area of 1.73 m2) was significantly higher in the diabetics than in 26 age-matched controls (127 +/- 21 ml/min vs. 107 +/- 15 ml/min, P less than 0.001). The same held true for the renal function assessed as the ratio GFR/ECV (0.58 +/- 0.10 hr-1 vs. 0.51 +/- 0.07, P less than 0.05). Regression analysis showed that the relation between ECV and body weight and between ECV and body surface area was the same in the diabetic patients as in 44 controls. The increased GFR but normal ECV indicates that the GFR alteration in diabetic patients reflects a real hyperfunction.

Relationship between glycosylation of haemoglobin and the duration of diabetes: a study during the third trimester of pregnancy

The relationship between blood glucose and glycosylated haemoglobin (HbAlc) had been investigated during an 8 week period in 53 Type 1 (insulin-dependent) diabetic women studied during the third trimester of pregnancy. Blood glucose estimations (fasting and 2h post-prandially) were made an average of 41 times in each patient during this period and HbAlc was determined once at the end of the study. There was a significant correlation between both the mean blood glucose over the preceding 8 weeks and the standard deviation of the fasting blood glucose with HbAlc (r = 0.69, p less than 0.001; r = 0.46, p less than 0.001, respectively). A "glycosylation index" was calculated for each patient (HbAlc divided by the mean blood glucose value). There was a significant correlation between the "glycosylation index" and duration of diabetes (r = 0.68, p less than 0.001). In contrast, there was no correlation between red cell 2,3-diphosphoglycerate and HbAlc or "glycosylation index". These findings suggest that increasing duration of diabetes influences the post-translational formation of HbAlc and that isolated HbAlc values need to be interpreted with caution in the pregnant diabetic.

Hemoglobin A1c determinations in diabetic pregnancy

To investigate the relationship of hemoglobin A1c (HbA1c) to average blood glucose concentration and to birth weight of infants of diabetic mothers, HbA1c was determined in 42 consecutive insulin-dependent pregnant diabetic women in the third trimester. HbA1c correlated significantly to the average blood glucose levels in the preceding 8 wk (r = 0.73, P less than 0.001). No correlation was found between HbA1c and the relative birth weight ratio (RBWR) for all newborn infants. However, in the major subgroups of pregnancies, White class B and C without prognostically bad signs in pregnancy (PBSP), HbA1c in the third trimester significantly correlated to RBWR (r = 0.59, P less than 0.01). In a subgroup of six pregnant diabetic women in whom HbA1c and blood glucose concentrations frequently were determined from the 13th to the 33rd gestational week, a relationship between HbA1c and the average blood glucose concentration of the preceding 8 and 12 wk in the individual pregnant subject was established. In spite of this correlation, HbA1c was found to be a poor predictor of the average blood glucose concentration in the individual patient. This indicates that HbA1c cannot satisfactorily describe the degree of diabetes control without simultaneous determinations of blood glucose. HbA1c determinations were found to be of value as an additional indicator of the quality of regulation during ambulatory control in diabetic pregnancy because an increase in HbA1c suggested an impairment of diabetic control. The perinatal mortality and morbidity of the infants of diabetic mothers were satisfactory in this series, as only one perinatal death, one nonserious malformation, and two cases of mild respiratory distress syndrome occurred among the 43 infants.