Obstetric Complications With GDM Effects of Maternal Weight MINDY GOLDMAN, JOHN L KITZMILLER, BARBARA ABRAMS, RONALD M. COWAN, AND RUSSELL K. LAROS, JR.
Obstetric complications recorded prospectively were assessed retrospectively in 150 women with gestational diabetes mellitus (GDM) and 305 control subjects matched for age, parity, and ethnicity. Intensive diet therapy and self-monitoring of capillary blood glucose were used to obtain postprandial euglycemia; 22% of GDM subjects required insulin. GDM and control subjects were grouped by body mass index to detect any influence of maternal prepregnancy weight on outcome. Polyhydramnios, preterm labor, and pyelonephritis were not more frequent in GDM, but hypertension without proteinuria (7.3 vs. 3.3%) and preeclampsia (8 vs. 3.9%) were more frequent in GDM. The frequency of hypertensive complications in GDM was not totally attributable to being overweight. Abnormalities of labor, birth trauma, and fetal macrosomia were not more common in GDM; 6.7% of the infants of mothers with GDM weighed >4200 g at birth compared with 3.6% of control infants (NS), and 10% were large for gestational age and sex compared with 6.6% of control infants (NS). Despite this, cesarean delivery was more common in GDM (35.3 vs. 22%, P < 0.01), mostly due to significantly more cesarean births without labor. Diabetes 40 (Suppl. 2): 79-82, 1991
I
n 1987, Cousins (1) reviewed the literature published in English from 1965 to 1985 on the impact of diabetes on the frequency and severity of obstetric complications. The paucity of information regarding maternal morbidity was noted due to the small number of controlled studies. In his compilation of 24 reports, maternal complications of interest with gestational diabetes mellitus (GDM) included hydramnios (5.3% of 133 women), pregnancy-induced hypertension (10% of 791), chronic hypertension (9.9% of 142), pyelonephritis (4% of 124), and delivery by cesarean section (20.4% of 800). Whether the apparent increased frequencies of obstetric complications are affected by con-
DIABETES, VOL. 40, SUPPL. 2, DECEMBER 1991
founding variables such as subject weight and age or hypertension is not clear from the published reports. The purpose of this study was to determine the frequency of obstetric complications in intensively treated women with GDM and matched control subjects from a local prenatal population in which universal screening for glucose intolerance was employed. We retrospectively analyzed data collected prospectively in a large perinatal data base and sought to determine the effect of maternal weight adjusted for height on hypertensive disorders, preterm labor, hydramnios, abnormalities of labor, and maternal and infant birth trauma. RESEARCH DESIGN AND METHODS
Perinatal data were prospectively collected by code sheets completed by attendees and residents. Chart abstractors filed the data into a computer-based program. Obstetric outcomes were studied for patients seen at the University of California, San Francisco, obstetric practice from July 1986 to November 1989. Maternal transports, women delivering more than once during this period, and women with fasting blood glucose (FBG) >7.2 mM were excluded. All patients were screened with a nonfasting 50-g 1-h glucose-loading test (GLT) at 14-28 wk gestation. A plasma threshold of 7.2 mM defined a positive screen. Patients with a positive screen underwent a 100-g 3-h oral glucose tolerance test (OGTT) after 3 days of 300 g of carbohydrate in the diet. Abnormal values were defined by the National Diabetes Data Group criteria of any two values >5.8 mM fasting, 10.6 mM at 1 h, 9.2 mM at 2 h, and 8.1 mM at 3 h (2). Those patients with an initial GLT >12.2 mM were classified as glucose intolerant and did not receive a standard 3-h OGTT.
From the Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco; and the School of Public Health, University of California, Berkeley, California. Address correspondence and reprint requests to John L. Kitzmiller, MD, Department of Obstetrics, Gynecology, and Reproductive Sciences, M1489, Box 0346, University of California, San Francisco, 505 Parnassus Avenue, San Francisco, CA94113.
79
OBSTETRIC COMPLICATIONS IN GDM
TABLE 1 Hypertensive complications in control and GDM subjects grouped by weight for height
Body mass index Pregravid weight relative to ideal (%) Hypertension without proteinuria (n) Control GDM Preeclampsia (n) Control GDM
Underweight
Ideal weight
Moderately overweight
Very overweight
135
1 of 64 (1.6) Oof 15
6 of 191 (3.1) 6 of 95 (6.3)
1 of 26 (3.8) 2 of 19(10.5)
2 of 24 (8.3) 3 Of 21 (14.3)
10 of 305(3.3) 11 of 150(7.3)*
2 of 64(3.1) Oof 15
7 of 191 (3.7) 8 of 95 (8.4)
1 of 26 (3.8) 2 of 19(10.5)
2 of 24 (8.3) 2 of 21 (9.5)
12 of 305(3.9) 12 of 150(8)
Total
Percentages are given in parentheses. GDM, gestational diabetes mellitus. * P = 0.05 vs. control.
All control subjects had a plasma glucose value 7.2 mM on >20% of the measurements. Nine subjects with a screening GLT > 12.2 mM did not have an OGTT, and 7 required insulin therapy. Of 141 subjects with an abnormal OGTT, 15.6% had FBG values >5.8 mM, but 59% of them did not require insulin therapy to remain normoglycemic. Of 119 subjects with an FBG on the OGTT 4200 g in an insulin-treated patient, delivery by primary cesarean section was recommended unless the woman had already safely delivered an infant of that size. Obstetric outcomes were analyzed in relation to body mass index (prepregnancy weight [kg]/height [cm2] multiplied by 10,000; 3). One hundred fifty GDM and 305 control subjects were included in the analysis of maternal and infant outcomes, which was carried out with the SPSS/PC + statis-
80
tical package (SPSS, Chicago, IL). The diagnosis of polyhydramnios was made by ultrasound examination (vertical pocket >8 cm). Preeclampsia was defined as acute hypertension and proteinuria in the second half of pregnancy. Preterm labor was defined by cervical change requiring intravenous tocolytic therapy. Labor abnormalities were as defined by Friedman (4). Infants small for gestational age (SGA) at birth weighed less than the 10th percentile for gestational age and sex in California (5), and infants large for gestational age (LGA) weighed more than the 90th percentile. Data were evaluated with Student's t test and contingency tables with appropriate adjustments. Significance was defined as P < 0.05, with two-tailed tests when relevant.
RESULTS
There was no significant difference between the control and GDM groups regarding polyhydramnios (0.7 vs. 2%), preterm labor (7.2 vs. 9.3%), or pyelonephritis (0.7 vs. 1.3%). Hypertension without proteinuria and preeclampsia was twice as common in women with GDM, differences that approached statistical significance at P = 0.05 and P = 0.07, respectively (Table 1). The association of maternal weight for height with hypertensive complications in both groups is illustrated in Table 1. Almost two-thirds of both control and GDM subjects were of ideal weight, but 21% of control subjects and 10% of GDM subjects were underweight (P = 0.03), 8.5% of control subjects and 12.7% of GDM subjects were moderately overweight (NS), and 7.9% of control subjects and 14% of GDM subjects were very overweight (P= 0.08). Due to a lack of statistical power from limited sample size within the body weight for height cells, the approximately twofold increased rates of hypertension and preeclampsia in the ideal-weight and moderately overweight GDM subjects were not significantly different from those of control subjects. Although hypertension without proteinuria was somewhat more common in the moderately and very overweight GDM subjects compared with glucose-intolerant subjects of ideal weight, the frequency of preeclampsia in GDM subjects was not solely attributable to increased body weight. Fetal macrosomia was not significantly more common in GDM in that 10% of infants of mothers with GDM were LGA compared with 6.7% of control infants, and 6.7% of infants of
DIABETES, VOL. 40, SUPPL. 2, DECEMBER 1991
M. GOLDMAN AND ASSOCIATES I
TABLE 2 Macrosomic infants of control and GDM subjects grouped by weight for height
Body mass index Pregravid weight relative to ideal (%) LGA infant (n) Control GDM Birth weight >4200 g (n) Control GDM
Underweight
Ideal weight
Moderately overweight
Very overweight
135
1 of 64 (1.6) Oof 15
14 of 191 (7.3) 9 of 95 (9.5)
Oof 26 4 of 19 (21.1)
5 of 24 (20.8) 2 of 21 (9.5)
20 of 301 (6.6) 15 of 150 (10.0)
1 of 64 (3.1) Oof 15
7 of 191 (3.7) 5 of 95 (5.3)
Oof 26 4 of 19 (21.1)
3 of 24 (8.3) 1 of 21 (4.8)
11 of 301 (3.7) 10 of 150 (6.7)
Total
Percentages are given in parentheses. GDM, gestational diabetes mellitus; LGA, large for gestational age (birth weight >90th percentile for gestational age and sex in California [5]).
mothers with GDM weighed >4200 g at birth compared with 3.6% of control infants (NS). The distribution of LGA or >4200-g infants in the maternal weight categories is given in Table 2. Apparently, more macrosomic infants were born of mothers with GDM in the moderately overweight category compared with mothers with GDM of ideal weight, but the differences were not significant due to the limited sample size in the cells. Of the 10 GDM mothers with infants >4200 g, 3 required insulin treatment (NS), and 2 had FBG values >5.8 mM (NS). SGA infants were delivered to 8.9% of control subjects and 4.5% of mothers with GDM. Most infants in both groups were born at term in that 9.5% of mothers with GDM and 6.9% of control subjects delivered at 5.3 mM. In the insulin-treated subgroup, there was no reported shoulder dystocia, but 16.2% of the 74 infants had birth weights >4000 g. However, fetal macrosomia was highly associated with morbid obesity in the mothers. In our study of GDM, the frequencies of macrosomia were not higher in infants of mothers with FBG >5.8 mM or who required insulin to become euglycemic. Unfortunately, the limited sample size within the maternal body weight groups prevents a detailed statistical analysis of the influence of maternal weight and weight gain on birth weight in this study. A much larger study is needed to determine whether macrosomic infants are more common in overweight mothers with GDM despite normoglycemia with diet therapy and whether so-called prophylactic insulin therapy would be useful (12,13). Despite "normal" frequencies of fetal macrosomia and abnormalities of labor in our GDM group, the cesarean section rate remained significantly higher than in matched control subjects (35.3 vs. 22%). Increased cesarean births occurred in both GDM subjects that attempted labor and those that did not and in both normal-weight and overweight GDM women. The determinants of the increased cesarean
82
section rates will be analyzed and reported separately, but we believe the explanation is probably related to patterns of physician decision making. REFERENCES 1. Cousins L: Pregnancy complications among diabetic women: review 1965-1985. Obstet Gynecol Surv 42:140-49, 1987 2. National Diabetes Data Group: Classification and diagnosis of diabetes mellitus and other categories of glucose intolerance. Diabetes 28:103957, 1979 3. GarrowJ: Treat Obesity Seriously. London, Churchill Livingstone, 1981, p. 175 4. Friedman EA: Patterns of labor as indicators of risk. Clin Obstet Gynecol 16:172-83, 1973 5. Williams RL, Creasy RK, Cunningham GD, Hawes WE, Norris FD, Tashiro M: Fetal growth and perinatal viability in California. Obstet Gynecol 59:624-32, 1982 6. Jacobson JD, Cousins L: A population-based study of maternal and perinatal outcome in patients with gestational diabetes. Am J Obstet Gynecol 161:981-86, 1989 7. Garner PR, DAIton MD, Dudley DK, Huard P, Hardie M: Preeclampsia in diabetic pregnancies. Am J Obstet Gynecol 163:505-508, 1990 8. Gabbe SG, Mestman JH, Freeman RK, Anderson GV, Lowensohn Rl: Management and outcome of class A diabetes mellitus. Am J Obstet Gynecol 127:465-69, 1977 9. Leikin E, Jenkins JH, Graves WL: Prophylactic insulin in gestational diabetes. Obstet Gynecol 70:587-92, 1987 10. Pettitt DJ, Knowler WC, Baird HR, Bennett PH: Gestational diabetes: infant and maternal complications of pregnancy in relation to thirdtrimester glucose tolerance in the Pima Indians. Diabetes Care 3:45864, 1980 11. Dandrow RV, O'Sullivan JB: Obstetric hazards of gestational diabetes. Am J Obstet Gynecol 96:1144-47, 1966 12. Coustan DR, Imarah J: Prophylactic insulin treatment of gestational diabetes reduces the incidence of macrosomia, operative delivery and birth trauma. Am J Obstet Gynecol 150:836-40, 1984 13. Persson B, Stangenberg M, Hansson U, Nordlander E: Gestational diabetes mellitus (GDM): comparative evaluation of two treatment regimens, diet versus insulin and diet. Diabetes 34 (Suppl. 2):101—103, 1985
DIABETES, VOL. 40, SUPPL. 2, DECEMBER 1991
Obstetric complications recorded prospectively were assessed retrospectively in 150 women with gestational diabetes mellitus (GDM) and 305 control subjects matched for age, parity, and ethnicity. Intensive diet therapy and self-monitoring of capillary blood glucose were used to obtain postprandial euglycemia; 22% of GDM subjects required insulin. GDM and control subjects were grouped by body mass index to detect any influence of maternal prepregnancy weight on outcome. Polyhydramnios, preterm labor, and pyelonephritis were not more frequent in GDM, but hypertension without proteinuria (7.3 vs. 3.3%) and preeclampsia (8 vs. 3.9%) were more frequent in GDM. The frequency of hypertensive complications in GDM was not totally attributable to being overweight. Abnormalities of labor, birth trauma, and fetal macrosomia were not more common in GDM; 6.7% of the infants of mothers with GDM weighed >4200 g at birth compared with 3.6% of control infants (NS), and 10% were large for gestational age and sex compared with 6.6% of control infants (NS). Despite this, cesarean delivery was more common in GDM (35.3 vs. 22%, P < 0.01), mostly due to significantly more cesarean births without labor. Diabetes 40 (Suppl. 2): 79-82, 1991
I
n 1987, Cousins (1) reviewed the literature published in English from 1965 to 1985 on the impact of diabetes on the frequency and severity of obstetric complications. The paucity of information regarding maternal morbidity was noted due to the small number of controlled studies. In his compilation of 24 reports, maternal complications of interest with gestational diabetes mellitus (GDM) included hydramnios (5.3% of 133 women), pregnancy-induced hypertension (10% of 791), chronic hypertension (9.9% of 142), pyelonephritis (4% of 124), and delivery by cesarean section (20.4% of 800). Whether the apparent increased frequencies of obstetric complications are affected by con-
DIABETES, VOL. 40, SUPPL. 2, DECEMBER 1991
founding variables such as subject weight and age or hypertension is not clear from the published reports. The purpose of this study was to determine the frequency of obstetric complications in intensively treated women with GDM and matched control subjects from a local prenatal population in which universal screening for glucose intolerance was employed. We retrospectively analyzed data collected prospectively in a large perinatal data base and sought to determine the effect of maternal weight adjusted for height on hypertensive disorders, preterm labor, hydramnios, abnormalities of labor, and maternal and infant birth trauma. RESEARCH DESIGN AND METHODS
Perinatal data were prospectively collected by code sheets completed by attendees and residents. Chart abstractors filed the data into a computer-based program. Obstetric outcomes were studied for patients seen at the University of California, San Francisco, obstetric practice from July 1986 to November 1989. Maternal transports, women delivering more than once during this period, and women with fasting blood glucose (FBG) >7.2 mM were excluded. All patients were screened with a nonfasting 50-g 1-h glucose-loading test (GLT) at 14-28 wk gestation. A plasma threshold of 7.2 mM defined a positive screen. Patients with a positive screen underwent a 100-g 3-h oral glucose tolerance test (OGTT) after 3 days of 300 g of carbohydrate in the diet. Abnormal values were defined by the National Diabetes Data Group criteria of any two values >5.8 mM fasting, 10.6 mM at 1 h, 9.2 mM at 2 h, and 8.1 mM at 3 h (2). Those patients with an initial GLT >12.2 mM were classified as glucose intolerant and did not receive a standard 3-h OGTT.
From the Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco; and the School of Public Health, University of California, Berkeley, California. Address correspondence and reprint requests to John L. Kitzmiller, MD, Department of Obstetrics, Gynecology, and Reproductive Sciences, M1489, Box 0346, University of California, San Francisco, 505 Parnassus Avenue, San Francisco, CA94113.
79
OBSTETRIC COMPLICATIONS IN GDM
TABLE 1 Hypertensive complications in control and GDM subjects grouped by weight for height
Body mass index Pregravid weight relative to ideal (%) Hypertension without proteinuria (n) Control GDM Preeclampsia (n) Control GDM
Underweight
Ideal weight
Moderately overweight
Very overweight
135
1 of 64 (1.6) Oof 15
6 of 191 (3.1) 6 of 95 (6.3)
1 of 26 (3.8) 2 of 19(10.5)
2 of 24 (8.3) 3 Of 21 (14.3)
10 of 305(3.3) 11 of 150(7.3)*
2 of 64(3.1) Oof 15
7 of 191 (3.7) 8 of 95 (8.4)
1 of 26 (3.8) 2 of 19(10.5)
2 of 24 (8.3) 2 of 21 (9.5)
12 of 305(3.9) 12 of 150(8)
Total
Percentages are given in parentheses. GDM, gestational diabetes mellitus. * P = 0.05 vs. control.
All control subjects had a plasma glucose value 7.2 mM on >20% of the measurements. Nine subjects with a screening GLT > 12.2 mM did not have an OGTT, and 7 required insulin therapy. Of 141 subjects with an abnormal OGTT, 15.6% had FBG values >5.8 mM, but 59% of them did not require insulin therapy to remain normoglycemic. Of 119 subjects with an FBG on the OGTT 4200 g in an insulin-treated patient, delivery by primary cesarean section was recommended unless the woman had already safely delivered an infant of that size. Obstetric outcomes were analyzed in relation to body mass index (prepregnancy weight [kg]/height [cm2] multiplied by 10,000; 3). One hundred fifty GDM and 305 control subjects were included in the analysis of maternal and infant outcomes, which was carried out with the SPSS/PC + statis-
80
tical package (SPSS, Chicago, IL). The diagnosis of polyhydramnios was made by ultrasound examination (vertical pocket >8 cm). Preeclampsia was defined as acute hypertension and proteinuria in the second half of pregnancy. Preterm labor was defined by cervical change requiring intravenous tocolytic therapy. Labor abnormalities were as defined by Friedman (4). Infants small for gestational age (SGA) at birth weighed less than the 10th percentile for gestational age and sex in California (5), and infants large for gestational age (LGA) weighed more than the 90th percentile. Data were evaluated with Student's t test and contingency tables with appropriate adjustments. Significance was defined as P < 0.05, with two-tailed tests when relevant.
RESULTS
There was no significant difference between the control and GDM groups regarding polyhydramnios (0.7 vs. 2%), preterm labor (7.2 vs. 9.3%), or pyelonephritis (0.7 vs. 1.3%). Hypertension without proteinuria and preeclampsia was twice as common in women with GDM, differences that approached statistical significance at P = 0.05 and P = 0.07, respectively (Table 1). The association of maternal weight for height with hypertensive complications in both groups is illustrated in Table 1. Almost two-thirds of both control and GDM subjects were of ideal weight, but 21% of control subjects and 10% of GDM subjects were underweight (P = 0.03), 8.5% of control subjects and 12.7% of GDM subjects were moderately overweight (NS), and 7.9% of control subjects and 14% of GDM subjects were very overweight (P= 0.08). Due to a lack of statistical power from limited sample size within the body weight for height cells, the approximately twofold increased rates of hypertension and preeclampsia in the ideal-weight and moderately overweight GDM subjects were not significantly different from those of control subjects. Although hypertension without proteinuria was somewhat more common in the moderately and very overweight GDM subjects compared with glucose-intolerant subjects of ideal weight, the frequency of preeclampsia in GDM subjects was not solely attributable to increased body weight. Fetal macrosomia was not significantly more common in GDM in that 10% of infants of mothers with GDM were LGA compared with 6.7% of control infants, and 6.7% of infants of
DIABETES, VOL. 40, SUPPL. 2, DECEMBER 1991
M. GOLDMAN AND ASSOCIATES I
TABLE 2 Macrosomic infants of control and GDM subjects grouped by weight for height
Body mass index Pregravid weight relative to ideal (%) LGA infant (n) Control GDM Birth weight >4200 g (n) Control GDM
Underweight
Ideal weight
Moderately overweight
Very overweight
135
1 of 64 (1.6) Oof 15
14 of 191 (7.3) 9 of 95 (9.5)
Oof 26 4 of 19 (21.1)
5 of 24 (20.8) 2 of 21 (9.5)
20 of 301 (6.6) 15 of 150 (10.0)
1 of 64 (3.1) Oof 15
7 of 191 (3.7) 5 of 95 (5.3)
Oof 26 4 of 19 (21.1)
3 of 24 (8.3) 1 of 21 (4.8)
11 of 301 (3.7) 10 of 150 (6.7)
Total
Percentages are given in parentheses. GDM, gestational diabetes mellitus; LGA, large for gestational age (birth weight >90th percentile for gestational age and sex in California [5]).
mothers with GDM weighed >4200 g at birth compared with 3.6% of control infants (NS). The distribution of LGA or >4200-g infants in the maternal weight categories is given in Table 2. Apparently, more macrosomic infants were born of mothers with GDM in the moderately overweight category compared with mothers with GDM of ideal weight, but the differences were not significant due to the limited sample size in the cells. Of the 10 GDM mothers with infants >4200 g, 3 required insulin treatment (NS), and 2 had FBG values >5.8 mM (NS). SGA infants were delivered to 8.9% of control subjects and 4.5% of mothers with GDM. Most infants in both groups were born at term in that 9.5% of mothers with GDM and 6.9% of control subjects delivered at 5.3 mM. In the insulin-treated subgroup, there was no reported shoulder dystocia, but 16.2% of the 74 infants had birth weights >4000 g. However, fetal macrosomia was highly associated with morbid obesity in the mothers. In our study of GDM, the frequencies of macrosomia were not higher in infants of mothers with FBG >5.8 mM or who required insulin to become euglycemic. Unfortunately, the limited sample size within the maternal body weight groups prevents a detailed statistical analysis of the influence of maternal weight and weight gain on birth weight in this study. A much larger study is needed to determine whether macrosomic infants are more common in overweight mothers with GDM despite normoglycemia with diet therapy and whether so-called prophylactic insulin therapy would be useful (12,13). Despite "normal" frequencies of fetal macrosomia and abnormalities of labor in our GDM group, the cesarean section rate remained significantly higher than in matched control subjects (35.3 vs. 22%). Increased cesarean births occurred in both GDM subjects that attempted labor and those that did not and in both normal-weight and overweight GDM women. The determinants of the increased cesarean
82
section rates will be analyzed and reported separately, but we believe the explanation is probably related to patterns of physician decision making. REFERENCES 1. Cousins L: Pregnancy complications among diabetic women: review 1965-1985. Obstet Gynecol Surv 42:140-49, 1987 2. National Diabetes Data Group: Classification and diagnosis of diabetes mellitus and other categories of glucose intolerance. Diabetes 28:103957, 1979 3. GarrowJ: Treat Obesity Seriously. London, Churchill Livingstone, 1981, p. 175 4. Friedman EA: Patterns of labor as indicators of risk. Clin Obstet Gynecol 16:172-83, 1973 5. Williams RL, Creasy RK, Cunningham GD, Hawes WE, Norris FD, Tashiro M: Fetal growth and perinatal viability in California. Obstet Gynecol 59:624-32, 1982 6. Jacobson JD, Cousins L: A population-based study of maternal and perinatal outcome in patients with gestational diabetes. Am J Obstet Gynecol 161:981-86, 1989 7. Garner PR, DAIton MD, Dudley DK, Huard P, Hardie M: Preeclampsia in diabetic pregnancies. Am J Obstet Gynecol 163:505-508, 1990 8. Gabbe SG, Mestman JH, Freeman RK, Anderson GV, Lowensohn Rl: Management and outcome of class A diabetes mellitus. Am J Obstet Gynecol 127:465-69, 1977 9. Leikin E, Jenkins JH, Graves WL: Prophylactic insulin in gestational diabetes. Obstet Gynecol 70:587-92, 1987 10. Pettitt DJ, Knowler WC, Baird HR, Bennett PH: Gestational diabetes: infant and maternal complications of pregnancy in relation to thirdtrimester glucose tolerance in the Pima Indians. Diabetes Care 3:45864, 1980 11. Dandrow RV, O'Sullivan JB: Obstetric hazards of gestational diabetes. Am J Obstet Gynecol 96:1144-47, 1966 12. Coustan DR, Imarah J: Prophylactic insulin treatment of gestational diabetes reduces the incidence of macrosomia, operative delivery and birth trauma. Am J Obstet Gynecol 150:836-40, 1984 13. Persson B, Stangenberg M, Hansson U, Nordlander E: Gestational diabetes mellitus (GDM): comparative evaluation of two treatment regimens, diet versus insulin and diet. Diabetes 34 (Suppl. 2):101—103, 1985
DIABETES, VOL. 40, SUPPL. 2, DECEMBER 1991
