ABSTRACT. Postnatal blood glucose and individual plasma free amino acid levels were measured in 14 newborn infants of diabetic mothers. All infants had a significantly lower blood glucose concentration than normal controls but no significant correlation was observed between the blood glucose values and any of the amino acids determined. As regards the quantitative and qualitative changes of the plasma aminogram, the total concentration of amino acids and the level of a few individual amino acids (glycine, alanine, taurine, and valine) were significantly elevated in hill-term babies. However, no significant difference was found in the total plasma concentration of amino acids between premature infants of diabetic mothers and prema ture control infants, but the plasma alanine level was higher in the former. It is of interest that total plasma amino acid, alanine, and glycine levels were elevated in the asphyxiated babies.
This suggests that the postnatal hyperaminoacidemia observed in infants of diabetic mothers was due to birth asphyxia rather than to impaired gluconeogenesis. The possible role of a defective gluconeogenesis in the etiology of postnatal hypoglycemia in infants of diabetic mothers is not supported by these data. Pediatrics 61:77-82, 1978, infants of
diabetic mothers, blood glucose, plasma amino acids, gluco neogenesis, asphyxia.
The blood glucose level falls precipitously after birth' in infants of diabetic mothers, which is generally regarded as a consequence of functional hyperinsulinism. There is much controversy as to whether the insulin level is still inappropriately high during hypoglycemia.23
Bloom and Johnston4 found an impairment of glucagon release in infants of diabetic mothers. These data suggest a more complex etiology of hypoglycemia in these infants.
Gluconeogenesis plays an essential role in maintaining the blood glucose concentration
during even short periods of fasting in both the adult and the newborn infant.57 Quantitatively the most important precursors for de novo synthesis of glucose are the amino acids, and characteristic plasma levels of glucogenic amino acids have been foimd in two clinically important hypoglycemic states, such as the transient hypo glycemia in the small-for-gestational-age new born infant6 7 and the ketotic hypoglycemia in children.8 Diabetic ketoacidosis is another condi tion that is characterized by a typical plasma amino acid pattern.@
PATIENTSANDMETHODS
Fourteen infants of diabetic mothers were studied. Six infants were delivered vaginally and eight by cesarean section. Pertinent data regard ing pregnancies, deliveries, and infants are shown in Table I. Some infants were referred to us and full documentation could not be obtained in all cases (management during both the last trimester and the delivery).
Blood was taken from a cephalic vein immedi ately. In most cases more than one sample was collected at various times within the first 12 hours of life when feeding was started. Hypoglycemic newborn babies were sampled prior to the start of a continuous glucose infusion. Seven infants were full term and seven were born before 37 weeks of gestation. Therefore two groups of control babies
Received August 10, 1976; revision accepted for publication May 12, 1977.
Supported by the Scientific Research Council, Ministry of Health, Hungary (3 23 0502 04 1/M).
ADDRESS FOR REPRINTS: (G.S.) Department of Pediat rics, University of Pécs,County Hospital, Pécs,Hungary.
PEDIATRICSVol. 61 No.1 January 1978 77
BloodGlucoseand Plasma Amino Acid Concentrations
in Infants of DiabeticMothers
GyulaSoltész,M.D., KárolySchultz, M.D., Julius Mestyán,M.D., and lmre Horváth,M.D.
From the Department of Pediatrics, tJnieersity of Pkcs, Pècs,and the Department of Pediatrics, County Hospital, GyOr, Hungary
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infantDuration of Maternal
Diabetes
(yr)Maternal
Daily
Insulin Dose
(iU)ParityPregnancy
ToxemiaPlacentalWeight (g)Apgar
Score
at 1 nunpHGestational
Age (lvk)BirthWeight
(g)Weight/
Gestational Age (%)115?1+48077.32372,85050-75213401—6007.
. .343,420> 903231—?47.45°382,190<
1041182—990?7.22363,800>
905Gestational.
. .2—56077.37404,400> 90610?1+75077.37°383,820>
907Gestational.
. .6?500?. .
.331,47010-25810505—?67.08342,700>
90910?2—52057.30353,520>
9010Gestational.
..3—54047.28374,370> 9011932?+?10.
. .403,37050-7512840?+?10.
. .384,500> 90133322—?10.
. .382,60010-25143Diet
only2—1007. . .394,400> 90
Full—termPreniatureWell-Nourishedinfants
ofPAppropriateinfants ofPDiabeticforDiabeticMothersGestational
AgeMothersGestational
age°(wk)38.6
38-4038.7 38-4033 31-3635
33-37Birth
weights° (g)3,206
2,600-3,6203,611 2,190-4,5001,792 1,250-2,4503,161 1,470-3,880Postnatal
age°(hr)9
3-125 1-129.7 3-125
1-12Blood
glucose (mg/100 ml,55 ±331.5 ±8 < .0554.5 ±632 ±6<
.05mean
± SE)Total
plasma amino acids1,777 ±522,168 ±122< .012,122 ±1262,254 ± 93NS(pmole/liter,
mean ± SE)n157117
TABLE I
CLINICAL DATA OF INFANTS OF DIABETIC MOTHERS STUDIED
°Intravenous bicarbonate was given previously.
mated ion-exchange chromatography (Beckman Multichrom 4225 analyzer). Amino acid analyses were made at the same time in all groups.
For statistical analysis Student's t test was used and regression equations were calculated by the method of least squares (paired analysis).
RESULTS
Mean gestational ages, birth weights, postnatal ages, and blood glucose and total free amino acid levels in the two control and two study groups of
TABLE II
were selected, the first consisting of 15 full-term, well-nourished infants and a second control group of 11 healthy premature babies (Table II). Two of the full-term and none of the preterm control babies were delivered by cesarean section. All (both control and study) patients were admitted during the same period when obstetric practice was practically the same.
The blood glucose level was estimated by the o-toluidine method'° and the plasma levels of 17 individual amino acids were measured by auto
GESTATIONAL AGES, BIRTH WEIGHTS, POSTNATAL AGES, AND BLOOD GLUCOSE AND TOTAL PLASMA AMINO ACID LEVELS
Well
Full-termPrematureInfantsPAppropriateinfantsPNourishedof
Diabetic
Mothersfor
Gestational
Ageof
Diabetic
Mothers
TABLE III
PLASMA CONCENTRATIONS OF 17 AMINO ACID5°
°Valuesexpressed in micromoles per liter; mean ±SE.
Taurine143±36NSAspartate47± ± 12296 ±33< .001257 ±15286
457NS54 ±543
±6NSGlutamate68
±5101 ±30NS47 ±584
±29NSCitrulline17
±223 ±5NS25 ±619
±5NSProline171
±10161 ± 11NS195 ±23171 ±23NSGlycine287
±14417 ±33< .01285 ±24369 ±37NSAlanine288
±16344 ±21< .05280 ±23401 ±30< .01Cystine62
±687 ±11NS76 ±1484
±10NSValine121
±5153 ± 13< .01160 ±10149 ±11NSMethionine26
±225 ±3NS24 ±329
±3NSIsoleucine37
±238 ±2NS51 ±337
±6NSLeticine68±473±4NS100±971±6<.05Tyrosine86
±659 ± 11NS146 ± 1882 ±9< .01Phenylalanine74
±359 ± 10NS114 ± 1190
±39NSLysine146
±10183 ±24NS186 ±20205 ±9NSHistidine97
±853 ±6< .00161 ±1291 ±26NSArginine38
±539 ±4NS61 ±1041
±13NSTotal1,777
±522,168 ± 122< .012,122 ±1262,254
±93NSn157117
infants are shown in Table II. The mean blood glucose concentration was strikingly similar in the control groups, and infants of diabetic mothers had significantly lower blood glucose levels
(P < .05). There was no significant difference in the total concentrations of 17 amino acids between the full-term and premature control groups of infants, suggesting poor correlation between gestational age and postnatal plasma free amino acid pattern. While in premature infants of diabetic mothers the total plasma amino acid concentration was not significantly elevated, in full-term infants it was found to be higher than in the normal full-term infants (P < .01). The aminogram of the four infants of non-insulin treated mothers did not differ significantly from that of the infants of insulin-treated mothers.
Table III summarizes the mean individual free amino acid levels in each group. Full-term infants of diabetic mothers had significantly higher taurine, glycine, alanine, and valine levels and only the concentration of histidine was lower than normal. In infants of diabetic mothers born before term a significantly elevated alanine and signifi cantly decreased leucine and tyrosine levels were observed.
Of the infants of diabetic mothers studied, nine infants (five full-term and four preterm) had a blood glucose concentration equal to or less than 30 mg/ 100 ml. When forming hypoglycemic and nonhypoglycemic groups, no significant differ ence was found in the concentrations of either individual amino acids between the two groups. It could therefore be expected that there was no significant correlation between blood glucose level and either of the amino acids considered as important glucose precursors. It should be noted that the group of infants of diabetic mothers studied constituted a heterogeneous infant popu lation. One common feature in the clinical condi tion of the infants was that part of them suffered from some degree of birth asphyxia. Seven asphyxiated infants of diabetic mothers had extreme hyperaminoacidemia (mean, 2,482 @.tmole/liter) and hyperalaninemia (mean, 482 @tmoIe/liter). The diagnosis of birth asphyxia was made on clinical grounds (perinatal history, Apgar score, clinical signs) and on arterial pH measurements only.
Asphyxiated infants of diabetic mothers had a mean Apgar score of 6 and a mean arterial pH of 7.20. It is important to note, however (Table I),
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Normalt infants
UncomplicatedofDiabetic
MotherstPComplicated
P TABLE IV
PLASMA CONCENTRATIONS OF 17 AMINo ACID5°
Taurine201 ±6258 ±37NS299
±57NSAspartate49
±333 ±4< .0158 ±7<
.01Glutamate60
±288 ±24< .0188
±24NSCitrulline21
±218 ±4NS20
±3NSProline182
±11140 ±17NS192 ±30NSGlycine286
±13282 ±27NS443 ±52<
.05Alanine286
±13298 ±24NS482 ±13<
.001Cystine77
±1195 ±33NS55 ±13NSValine137
±7160 ±14NS161 ±21NSMethionine25
±221 ±2NS32 ±4<
.05Isoleucine43
±235 ±8NS43
±5NSLeucine82
±665 ±7NS80
±11NSTyrosine112
±1065 ±11< .0576 ±19NSPhenylalanine91
±694 ±17NS108
±14NSLysine164
±11220 ±24< .05200
±16NSHistidine71
±776 ±13NS102
±20NSArginine49
±642 ±5NS43
±5NSTotal1,936
±711,990 ±216NS2,482 ±120<
.01n2687
°Valuesexpressed in micromoles per liter; mean ±SE. tFull-term and premature infants.
associated with the deterioration of the infants' clinical condition (apnea spells, dyspnea, tachy cardia).
It was possible to make simultaneous measure ments of maternal and umbilical venous free amino acids in eight cases. Total plasma amino acid concentration was more than 20% higher in the umbilical vein than in the maternal circula tion (2,400 ±122 @.tmole/liter versus 1,980 ±165
.tmole/liter) but this difference was not signifi cant (P > .05). Of the individual amino acids only taurine, valine, and lysine had significantly higher umbilical than maternal venous levels. When the maternal and umbilical total amino acid concentrations were related to each other (Fig. 2), a significant positive linear correlation was found (r = .837, P < .01). A sufficient number of esti mations was available for 13 individual amino acids, and five out of 13 gave a significant positive correlation between maternal and umbilical levels (glycine, alanine, isoleucine, leucine, and lysine).
Finally, daily insulin doses given to the mothers were related to neonatal blood glucose and umbil ical free amino acid levels but no significant correlation was found. An insufficient number of that some infants of diabetic mothers received
intravenous bicarbonate prior to pH measure ments. The patients were reorganized into uncomplicated and complicated (asphyxiated) groups and premature and full-term controls were considered as one group, accordingly (Table IV). It is more clearly seen that hyperaminoacidemia was largely due to asphyxia, and with few excep tions plasma amino acid levels were very similar in the normal and in the “¿uncomplicated―groups. In fact, a large increase in the levels of alanine and glycine was responsible for the hyperamino acidemia of the asphyxiated group.
The high plasma alanine level in asphyxiated babies (Fig. 1) did not follow the normal postnatal pattern of gradual decline. A more delayed decrease or considerable fluctuation with large postnatal increases could be observed in some cases especially within the first 12 hours. All five infants in Figure 1 received intravenous glucose infusions (10% glucose, 80 to 120 ml/kg/24 hr). Since blood sampling time was not uniform in these cases during the infusions, aminograms were not evaluated statistically.
3000
. 700600
500
-@ @00
E
300
200
100
hours
FIG. 1. Postnatal changes of plasma alanine levels in five
severely asphyxiated infants of diabetic mothers. Shaded area indicates normal newborn infants (mean ±2 SD).
measurements prevented us from relating mater nal insulin doses to maternal plasma free amino acid levels.
Infants of diabetic mothers may show profound, though often asymptomatic, hypogly cemia immediately after birth, and protracted and severe hypoglycemia may also occur. Hyper insulinism seems to have a primary etiologic role,― but the impairment of glucagon release4 and the lack of elevation of plasma free fatty acid levels in hypoglycemia'2 are suggestive of a more complex etiology.
The role of gluconeogenesis has not yet been evaluated and data on plasma amino acid levels are rather scarce.―'4 This article reports on hyperaminoacidemia and hyperalaninemia in full-term infants of diabetic mothers which, according to recent reports,@
@ are characteristic
features of the plasma aminogram of hypogly cemic small-for-gestational-age infants. It is assumed that a delayed maturation or a transient defect of one or more key hepatic gluconeogenic enzymes led to decreased hepatic uptake and hence an elevated plasma concentration of these amino acids. The comparison of the aminograms of infants of diabetic mothers and small-for gestational-age babies revealed some further simi larities inasmuch as hyperglycinemia and hyper alaninemia accounted for a large portion of the
0
E
I2000
S•¿â€¢
r =0,8373 p<0,01
y=1173#0,6198x
1000
‘¿i:.
2@ FIG.2. Maternaland umbilical total amino acid concentra tions in diabetes.
increment in total plasma amino acids in both conditions. In infants of diabetic mothers, however, no significant difference was observed in the individual amino acids between hypogly cemic and nonhypoglycemic babies and there was no correlation between blood glucose and plasma amino acids.
Insulin suppresses gluconeogenesis from all precursors by reducing hepatic uptake'@ and by
decreasing substrate availability. ‘¿@“¿@Hyperinsu linism results in hypoaminoacidemia and a partic ularly marked decline occurs in the concentration of the branched-chain amino acids, tyrosine and phenylalanine.5 Alanine is unique because it is the only amino acid whose plasma concentration does not show a consistent decline, and, in fact, it may even increase under the influence of insu lin.'7 The aminogram observed did not show any characteristics of hyperinsulinism.
Glucagon is a potent stimulus of gluconeogen esis and the reported hypoglucagonemia in infants of diabetic mothers may be another factor in delaying the activation of neonatal gluconeo genesis. Since glucagon has a strong hypoalanin emic effect, glucagon insufficiency' may have contributed to the observed hyperalaninemia. A further factor in the pathogenesis of hyperami noacidemia could be birth asphyxia. It is probably the lactate accumulation itself that led to hyper alaninemia.'9 In the present study plasma alanine concentrations could not be related to blood lactate levels, but it was striking that deteriora tion in the clinical condition of the infants leading to hypoxia resulted in an immediate elevation of
woo
2000
3000
Maternal @pmo(/(
cord 12
DISCUSSION
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the plasma alanine level. This appears to be an indirect indication that hyperaminoacidemia and hyperalaninemia in full-term infants of diabetic mothers were probably the consequence of tissue hypoxia rather than the results of inefficient gluconeogenesis. The reorganization of data into uncomplicated and complicated (asphyxiated) groups clearly supports this.
When comparing maternal and umbilical free amino acid levels, five out of the 13 amino acids examined gave significant positive correlations, which is in agreement with the data of Cockburn et al.'3 This relationship was apparently not found in normal pregnancy,'32° and it was suggested that the exogenous insulin received by these mothers maintained an independent amino acid relationship across the placenta.
REFERENCES
1. Pildes RS: Infants of diabetic mothers. N Engl I Med 289:902, 1973.
2. King CK, Adam PAJ, Clemente AG, Schwartz R: Infants of diabetic mothers: Attenuated glucose uptake without hyperinsulinaemia during continuous glu cose infusion. Pediatrics 44:381, 1970.
3. Martin FIR, Dahlenburg A, Russel J, Jeffery P: Neonatal hypoglycaemia in infants of insulin dependent diabetic mothers. Arch Dis Child 50:472, 1975. 4. Bloom SR, Johnston DI: Failure of glucagon release in
infants of diabetic mothers. Br Med I 4:453, 1972. 5. Felig P, Owen OE, Wahren J, Cahill GF: Plasma amino acid metabolism during prolonged starvation. I Clin invest 48:584, 1969.
6. Haymond MW, Karl IE, Pagliara AS: Increased gluco neogenic substrates in the small-for-gestational-age infant. N Engl I Med 291:322, 1974.
7. Niestyán J, SoltészG, Schultz K, Horváth M: Hyper
aminoacidaemia due to the accumulation of gluco neogenic amino acid substrates in small-for-gesta
tional-ageinfants.I Pediatr 87:409, 1975. 8. Pagliara AS, Karl IE, De Vivo DC, et a!: Hypoala
ninaemia: A concomitant of ketotic hypoglycaemia. I Clininvest51:1440,1972.
9. Felig P, Marliss E, Ohman L, Cahill GF: Plasma amino acid levels in diabetic ketoacidosis. Diabetes 19:727, 1970.
10. Price JD: A simple, rapid method for determining glucose in blood and plasma. Analyst 92:198, 1967.
11. Block MB, Pildes RS, Moosybhoy NA, et al: C-Peptide immunoreactivity (CPR): A new method for studying infants of insulin-treated diabetic mothers.
Pediatrics 53:923, 1974.
12. Melichar V, Novak M, Hahn P, Koldovsky 0: Free fatty acids and glucose in the blood of various groups of newborns. Acta Paediatr Scand 53:343, 1964. 13. Cockburn F, Blagden A, Michie EA, Forfar JO: The
influence of preeclampsia and diabetes mellitus on plasma free amino acids in maternal umbilical and infant blood. I Obstet Gynaecol Br Commonw 78:215, 1971.
14. Reisner SH, Aranda JV, Colle E, et al: The effect of glucagon on plasma amino acids in the newborn.
Pediatr Res 79:184, 1973.
15. Felig P: Amino acid metabolism in man. Annri Rev
Biochem 44:933, 1975.
16. HimmshagenJ: The effects of insulin on the concentra
tion of plasma glycerol. I Lipid Res 4:446, 1963. 17. Felig P, Wahren J: Protein turnover and amino acid
metabolism in the regulation of gluconeogenesis. Fed Proc33:1092,1974.
18. Luck JM, Morris G, Wilbur LF: Effect of insulin on amino acid content of blood. I Biol Clieni 77:151, 1928.
19. Scriver CR, Rosenberg LF: Amino Acid Metabolism and
Its Disorders. Philadelphia, WB Saunders Co, 1973,
p 440.
20. Young M, Prenton MA: Maternal and fetal plasma amino acid concentrations during gestation and in retarded fetal growth. I Obstet Gynaecol Br
Commonw 76:333, 1969.
SCREENING
In principle we should prefer in medicine never to use diagnostic or therapeutic measures whose value has not been established, but in clinical practice, where the patient seeks medical assistance, it is often necessary to do so. In screening, however, where investigation is initiated by the physician, unvalidated procedures should have no place.
T. MCKEOWN Noted by R.J.H.
1978;61;77
Pediatrics
Gyula Soltész, Károly Schultz, Julius Mestyán and Imre Horváth
Blood Glucose and Plasma Amino Acid Concentrations in Infants of Diabetic Mothers
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1978;61;77
Pediatrics
Gyula Soltész, Károly Schultz, Julius Mestyán and Imre Horváth
Blood Glucose and Plasma Amino Acid Concentrations in Infants of Diabetic Mothers
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