Declining insulin requirement in the late first trimester of diabetic pregnancy

OBJECTIVE

To investigate whether pregnancies complicated by type 1 diabetes are associated with a decrease in first-trimester insulin requirement.

RESEARCH DESIGN AND METHODS

We examined the weekly insulin requirement (as units per kilogram per day) during the first trimester of pregnancy in diabetic women in the Diabetes in Early Pregnancy Study (DIEP) with accurate gestational dating, regular glucose monitoring, daily insulin-dose recording, and monthly glycohemoglobin measurements.

RESULTS

In pregnancies that resulted in live-born full-term singleton infants, a significant 18% increase in mean weekly dosage was observed between weeks 3 and 7 (P = 0.000), followed by a significant 9% decline from week 7 through week 15 (P = 0.000). Further testing localized a significant change in insulin dose in the interval beginning weeks 7-8 and ending weeks 11-12 (P = 0.014). Within this interval, the maximum decrease was between weeks 9 and 10 (mean), 10 and 11 (median), and 8 and 9 (most frequent maximal decrease). To determine whether prior poor glucose control exaggerated these trends, we categorized the women based on their glycohemoglobin values: <2 SDs above the mean of a normal population (subgroup 1), 2-4 SDs (subgroup 2), and >4 SDs (subgroup 3) at baseline. Late first-trimester declines in dosage were statistically significant in subgroup 2 (P = 0.002) and subgroups 2 and 3 together (P = 0.003). Similarly, women with BMI >27.0 had a greater initial insulin rise and then fall compared with leaner women.

CONCLUSIONS

Observations in the DIEP cohort disclose a mid-first-trimester decline in insulin requirement in type 1 diabetic pregnant women. Possible explanations include overinsulinization of previously poorly controlled diabetes, a transient decline in progesterone secretion during the late first-trimester luteo-placental shift in progesterone secretion, or other hormonal shifts. Clinicians should anticipate a clinically meaningful reduction in insulin requirement in the 5-week interval between weeks 7 and 12 of gestation.

Temporal trends in spontaneous abortion associated with Type 1 diabetes

The objective of this study was to investigate temporal changes in the reported rates of spontaneous abortion associated with Type 1 diabetes. Individuals from the Children's Hospital of Pittsburgh Type 1 Diabetes Registry for 1950-1964 (n=495) completed a self-report reproductive history questionnaire in 1981 that was updated in 1990. Data from both surveys, which proved to be valid and reliable, were utilized for this report. More spontaneous abortions (26.8 vs. 7.7%, P<0.001), stillbirths (4.7 vs. 1.2%, P<0.001) and induced abortions (7.0 vs. 0.9%, P<0.001) were reported for Type 1 diabetic women than for the non-diabetic partners of Type 1 diabetic men. A significant temporal decline in the rates of spontaneous abortion for Type 1 diabetic women was observed (< or = 1969: 26.4%; 1970-1979: 31.0%; 1980-1989: 15.7%; P<0.05). No differences were apparent for the non-diabetic partners of Type 1 diabetic men (< or = 1969: 4.2%; 1970-1979: 9.5%; 1980-1989: 5.7%; P>0.05). Temporal changes in medical care for women with diabetes (i.e. self-monitoring of glycemic control) may have contributed to a recent reduction in spontaneous abortions associated with maternal Type 1 diabetes.

The Diabetes in Early Pregnancy Study: beta-hydroxybutyrate levels in type 1 diabetic pregnancy compared with normal pregnancy. NICHD-Diabetes in Early Pregnancy Study Group (DIEP). National Institute of Child Health and Development

OBJECTIVE

The objective was to assess relationships between beta-hydroxybutyrate (beta-OHB) level and pregnancy outcome in human pregnancy in light of the fact that high levels of beta-OHB cause malformations and growth retardation in in vitro studies.

RESEARCH DESIGN AND METHODS

We analyzed beta-OHB in prospectively collected specimens from the National Institute of Child Health and Human Development-Diabetes in Early Pregnancy Study, in gestational weeks 6-12 in diabetic (n = 204-239) and nondiabetic (n = 316-332) pregnant women.

RESULTS

Levels of beta-OHB in diabetic women were 2.5-fold higher than in nondiabetic pregnant women at 6 weeks' gestation and declined to 1.6-fold above nondiabetic women by 12 weeks' gestation (P < 0.0001 at all times). beta-OHB was positively correlated with glucose levels (P < 0.0001) in diabetic mothers, probably reflecting degree of diabetic control. beta-OHB correlated inversely with glucose (P < 0.0003) (gestational week 6 only) in nondiabetic mothers, possibly reflecting caloric intake. beta-OHB tended to be lower (not higher) in diabetic and nondiabetic mothers with malformed infants or pregnancy losses, but the difference was not statistically significant. beta-OHB in diabetic mothers at 8, 10, and 12 weeks correlated inversely with birth weight (P = 0.004-0.02), even after adjusting for maternal glucose levels. beta-OHB levels were also generally lower in diabetic mothers of macrosomic infants, and week 12 ultrasound crown-rump measurements were inversely related to beta-OHB levels.

CONCLUSIONS

The lst trimester beta-OHB is significantly higher in diabetic than nondiabetic pregnant women. In both groups, beta-OHB tended to be lower, not higher, in mothers who had a malformed infant or pregnancy loss. beta-OHB was inversely related to crown-rump length and birth weight. The modest beta-OHB elevation in the 1st trimester of reasonably well-controlled diabetic pregnancy is not associated with malformations, probably because beta-OHB levels causing malformations in embryo culture models are 20- to 40-fold higher. The mechanism of the beta-OHB association with impaired fetal growth is unknown.

Moderate caffeine use and the risk of spontaneous abortion and intrauterine growth retardation

OBJECTIVE

To examine the relationship between caffeine consumption during pregnancy and the occurrence of spontaneous abortion and intrauterine growth retardation.

DESIGN, SETTING, AND PATIENTS

A cohort of 431 women, enrolled in a multicenter study within 21 days of conception, was monitored throughout pregnancy to determine (1) caffeine exposure, (2) exposure to other risk factors, (3) fetal growth as assessed by ultrasonography, and (4) pregnancy outcome.

OUTCOME MEASURES

Spontaneous abortion, intrauterine growth, birth weight, and head circumference.

RESULTS

The mean (+/- SD) first-trimester caffeine consumption was not significantly higher in women who aborted (125.9 +/- 123.1 mg) than in women who delivered liveborn infants (111.6 +/- 107.0 mg) (P = 34). The adjusted odds ratio (OR) for spontaneous abortion was 1.15 (95% confidence interval [CI], 0.89 to 1.49). Early fetal growth, assessed by crown-rump length on ultrasonographic examination, was not affected by caffeine. Although the group consuming the most caffeine (> 300 mg/d) had a significantly higher proportion of babies with birth weights and head circumferences below the 10th percentile in the crude analysis, the association with caffeine was no longer significant when other risk factors (notably smoking) were taken into account. The adjusted ORs were 1.11 (95% CI, 0.88 to 1.40) for decreased birth weight and 1.09 (95% CI, 0.86 to 1.37) for smaller head circumference.

CONCLUSIONS

Close monitoring of a cohort identified very soon after conception enabled us to identify all abortions after 21 days postconception, monitor intrauterine growth prospectively, and track caffeine use. Despite this intensive surveillance, we found no evidence that moderate caffeine use increased the risk of spontaneous abortion, intrauterine growth retardation, or microcephaly after accounting for other risk factors.

Early sonographic evaluation for fetal growth delay and congenital malformations in pregnancies complicated by insulin-requiring diabetes. National Institute of Child Health and Human Development Diabetes in Early Pregnancy Study

OBJECTIVE

It has been reported that early fetal growth retardation may be a useful marker for congenital malformations in diabetic pregnancies. To test this hypothesis, diabetic and nondiabetic women were sonographically evaluated during the first trimester.

RESEARCH DESIGN AND METHODS

Fetal crown-rump lengths were measured sonographically at least once during the first 15 wk of pregnancy in 329 nondiabetic and 312 diabetic women. Of these, 289 nondiabetic and 269 diabetic women had sonograms before 10 wk of gestation and 283 nondiabetic and 269 diabetic women had sonograms between 10 and 15 wk of gestation. Early fetal growth delay was defined as a sonographic gestational age of greater than or equal to 6 days less than menstrual gestational age.

RESULTS

The mean crown-rump lengths at 8 wk were 17.9 +/- 4.6 mm in the diabetic and 18.7 +/- 4.9 mm in the nondiabetic groups (P = 0.13). At 12 wk, the mean fetal crown-rump length was 58.5 +/- 8.8 mm for diabetic subjects and 60.6 +/- 8.7 mm for nondiabetic subjects (P = 0.04). Between 5 and 9 wk, 28 of 289 (9.7%) fetuses of nondiabetic subjects, 34 of 259 (13.1%) normal fetuses of diabetic subjects, and 2 of 10 (20%) malformed fetuses of diabetic subjects demonstrated growth delay (P = 0.31, normal vs. malformed diabetic). Between 10 and 15 wk of gestation, 28 of 283 (9.9%) fetuses of nondiabetic subjects, 32 of 256 (12.5%) normal fetuses of diabetic subjects, and 4 of 13 (30.8%) malformed fetuses of diabetic subjects demonstrated growth delay (P = 0.06, normal vs. malformed diabetic). Early fetal growth delay did not predict a reduced birth weight at term.

CONCLUSIONS

Among insulin-dependent diabetic subjects who were moderately well controlled at conception, statistically significant but mild early fetal growth delay was present but did not appear to be useful clinically in predicting congenital malformations. Recommendations that growth delay demonstrated on early ultrasound be used as a predictor of congenital malformation require careful reexamination.

The Diabetes in Early Pregnancy Study: changes in cholesterol, triglycerides, body weight, and blood pressure. The National Institute of Child Health and Human Development--the Diabetes in Early Pregnancy Study

This study examined changes in cholesterol, triglycerides, body weight, and blood pressure during pregnancy in 312 diabetic and 356 control women recruited within 21 days after conception. Cholesterol values rose in both groups but were significantly lower in diabetic women at each time point (166 vs 178 mg/dl at week 12, p = 0.0004). Triglyceride values also rose in both groups. Triglyceride levels did not differ between groups up to week 8 of gestation, but by weeks 10 to 12 they were significantly lower in diabetic women than in controls (75 vs 89 mg/dl at week 12, p = 0.0004). Although they were no heavier at entry, diabetic women gained significantly more weight between weeks 6 and 8 (p less than 0.001), resulting in a mean difference between groups of 1 kg. Systolic blood pressure increased steadily and significantly in the diabetic but not the control women (115.8 +/- 16.2 SD vs 109.3 +/- 11.8 mm Hg, p = 0.0006 at term). Diastolic blood pressure was higher in diabetic women on entry (70.7 vs 67.3 mm Hg, p = 0.0006) and throughout gestation. Significant correlations were found in the diabetic group between maternal blood pressure and lipids and infant birth weight. These newly found differences in cholesterol and triglyceride levels, weight gain, and blood pressure between type I diabetic and control women during gestation may have long-term cardiovascular implications.

Maternal postprandial glucose levels and infant birth weight: the Diabetes in Early Pregnancy Study. The National Institute of Child Health and Human Development--Diabetes in Early Pregnancy Study

The cause of macrosomia in the infant of the diabetic woman is still not completely defined. The National Institute of Child Health and Human Development--Diabetes in Early Pregnancy Study, which recruited insulin-dependent diabetic and control women before conception, provided an opportunity to address the relationship between maternal glycemia and percentile birth weight. Data were analyzed from 323 diabetic and 361 control women. Fasting and nonfasting venous plasma glucose were measured on alternate weeks in the first trimester and monthly thereafter. Glycosylated hemoglobin was measured weekly in the first trimester and monthly thereafter. More infants of the diabetic women were at or above the 90th percentile for birth weight than infants of control women (28.5% versus 13.1%, p less than 0.001). Although first-trimester nonfasting glucose and glycosylated hemoglobin levels were positively correlated with infant birth weight (p less than 0.001 and p = 0.008), when the analyses were adjusted for the variables of the subsequent trimesters the values became insignificant, whereas the third-trimester nonfasting glucose levels adjusted for values in prior trimesters emerged as the stronger predictor of percentile birth weight (p = 0.001). After adjusting for maternal hypertension, smoking, and ponderal index, the above relationships remained. In conclusion, monitoring of nonfasting glucose levels rather than the fasting levels, which are more commonly monitored in clinical practice, are necessary to prevent macrosomia.

Drug ingestion during pregnancy: infrequent exposure in a contemporary United States sample. National Institute of Child Health and Human Development Diabetes in Early Pregnancy Study Group

Drug ingestion in a cohort of United States women proved consistently lower than in prior United States populations. Participating were 342 insulin-dependent diabetic and 387 control subjects who were enrolled before conception (76%) or no later than 21 days after conception (24%). Drug exposures were then recorded at entry and periodically throughout organogenesis (gestational weeks 6, 8, 10). During gestational weeks 1 to 10, approximately two thirds of the subjects were exposed to no agent other than oral iron, oral vitamins, or insulin (diabetic subjects). The mean exposures in gestational weeks 1 to 10 were 0.72 +/- 1.05 (SD) for diabetic women and 0.54 +/- 0.96 for control subjects; throughout pregnancy, the mean exposures were 1.26 +/- 1.66 and 1.58 +/- 1.78, respectively. The low exposure frequency in this contemporary United States population is highly encouraging. However, it follows that collaborative cohort efforts may be necessary in order to assess teratogenicity of drugs because relatively few women are now exposed.

Incidence of spontaneous abortion among normal women and insulin-dependent diabetic women whose pregnancies were identified within 21 days of conception

Whether pregnant women with insulin-dependent diabetes mellitus have an increased risk of spontaneous abortion is controversial. To address this question, we enrolled 386 women with insulin-dependent diabetes and 432 women without diabetes before or within 21 days after conception and followed both groups prospectively. Sixty-two diabetic women (16.1 percent) and 70 control women (16.2 percent) had pregnancy losses (odds ratio, 0.99; 95 percent confidence interval, 0.67 to 1.46). After adjustment for known risk factors for spontaneous abortion, the rate was still not significantly higher in the diabetic group (odds ratio, 0.91; 95 percent confidence interval, 0.59 to 1.40). Nonetheless, among the diabetic women, most of whom had good metabolic control, those who had spontaneous abortions had higher fasting and postprandial glucose levels in the first trimester than those whose pregnancies continued to delivery (P = 0.01 for fasting glucose levels and P = 0.005 for postprandial levels). In the small subgroup of diabetic women with poor control, who had elevated values for glycosylated hemoglobin in the first trimester, each increase of 1 SD above the normal range was associated with an increase of 3.1 percent in the rate of pregnancy loss (95 percent confidence interval, 0.6 to 5.6). We conclude that diabetic women with good metabolic control are no more likely than nondiabetic women to lose a pregnancy, but that diabetic women with elevated blood glucose and glycosylated hemoglobin levels in the first trimester have a significantly increased risk of having a spontaneous abortion.

Evaluation of methods for the prospective identification of early fetal losses in environmental epidemiology studies

A major problem in the epidemiologic investigation of early fetal losses has been incomplete or biased ascertainment. In order to assess early fetal losses more accurately, one must first develop a simple method to identify early pregnancy. This study, conducted at the University of Pittsburgh from October 1985 through October 1986, has developed such a method through the use of monoclonal antibody urine pregnancy testing kits. A total of 88 volunteers collected urine samples beginning on the seventh postovulatory day and continued until either menses occurred or a serum radioimmunoassay pregnancy test was performed on day 16. If pregnancy was diagnosed, all of the participants' urine specimens from that menstrual cycle were analyzed by five monoclonal antibody tests. A total of 34 pregnancies were diagnosed, six (18%) of which resulted in early fetal losses. Pregnancy was first detectable between eight and 18 days postovulation. The mean time to the first positive test was 14 days for all five kits. The results indicate that it is possible to diagnose early pregnancy with urine testing and that this method is likely to prove acceptable for use in large-scale prospective studies.

Lack of relation of increased malformation rates in infants of diabetic mothers to glycemic control during organogenesis

To determine how much insulin-dependent diabetes increases a woman's risk of giving birth to a malformed infant and how that risk is influenced by metabolic control, we followed 347 diabetic and 389 control women who enrolled in the study within 21 days of conception (the early-entry group) and 279 diabetic women who entered later (the late-entry group). We detected major malformations in the infants of 4.9 percent of the early-entry diabetic women, 2.1 percent of the controls, and 9.0 percent of the late-entry diabetic women. Malformation rates were significantly higher among offspring of early-entry diabetic women than among those of controls (odds ratio, 2.45; lower one-sided 95 percent confidence limit, 1.12; P = 0.027), and higher among late-entry than among early-entry diabetic women (odds ratio, 1.91; lower one-sided 95 percent confidence limit, 1.07; P = 0.032). Mean blood glucose and glycosylated hemoglobin levels during organogenesis were not significantly higher in women whose infants were malformed. Hypoglycemia (glucose, less than or equal to 50 mg per deciliter [2.8 mmol per liter]) was not significantly more common in the same group. Hyperglycemia and glycosylated hemoglobin were not correlated with malformation. The data suggest that more sensitive measures are needed to identify the teratogenic mechanisms, or that not all malformation can be prevented by good glycemic control. Despite the increased malformation rate among infants of the early-entry diabetic women, as compared with the controls, the more favorable outcome seen in the former group as compared with the late-entry group justifies the attempt to achieve good metabolic control around the time of conception.

Insulinoma in a 94-year-old woman: long-term therapy with verapamil

Several drugs can be used to control hypoglycemia caused by insulin-secreting pancreatic tumors but none are reliably efficacious or free of side effects. We report the case of a woman with an insulinoma who refused surgical intervention and was successfully treated with the Ca2+-channel blocker verapamil.

Utility of equivocal glucose tolerances

Interpretation of the results of an oral glucose tolerance test is simplified when the results are expressed as the Glucose Tolerance Sum for two or for three hours (GTS0-2 hr and GTS0-3 hr.).

The GTS0-2 hr value is the sum of the 0, ½, 1 and 2-hr, glucose levels in venous blood when 1.75 gm. of glucose are administered per kilogram of body weight. Data from more than 1,100 such tolerances indicate that when GTS0-2 hr is 500 or less there is a 98 to 100 per cent probability that the test is clearly normal by the standards of the World Health Organization, British Diabetic Association, United States Public Health Service, and Fajans and Conn of what is and what is not diabetes mellitus. On the other hand, when the GTS0-2 hr is 801 or higher the test would meet each of the four sets of above cited criteria for diabetes. Since those values between 501 and 800 are variably classifiable as normal or abnormal by these same four standards, this represents the equivocal zone.

The GTS0-3 hr value is based on the sum of 0, 1, 2, and 3-hr, blood glucose levels in the above tolerance tests. Using the same criteria, clearly nondiabetic tolerance tests yield GTS0-3 hr values of 450 or less, while those deemed to be diabetic have sums of 701 or higher. Intervening GTS0-3 hr values of 451 to 700 represent the equivocal zone.

Tolerance tests with GTS values in the equivocal zone should be repeated at intervals of months or years. In our experience equivocal tests generally move toward or into the abnormal range, a minority move back into the normal zone, and some remain equivocal.