Abstract
Objectives
There is a high prevalence of type 2 diabetes among Micronesians leading to the assumption that they are at an increased risk for gestational diabetes. The objective of this study was to determine the prevalence of gestational diabetes among the Micronesian population in Honolulu, Hawai'i. Secondary objectives were to determine factors associated with gestational diabetes and compare maternal and fetal outcomes between the Micronesian gestational diabetic and non-diabetic populations.
Methods
A retrospective chart review was performed of all delivery records from January 1997 to December 2006. Data were analyzed using measures of association and multiple logistic regression.
Results
Of the 2966 charts reviewed, 2303 met inclusion criteria. The prevalence of gestational diabetes was 6.2% and the prevalence of type 2 diabetes was 0.8%. In comparison to the non-diabetic group, the gestational diabetic population was significantly older (p=0.002) and heavier (p<0.001). Micronesians with gestational diabetes had higher rates of cesarean section and hypertensive disorders. However, rates of shoulder dystocia were not statistically different. Infants of gestational diabetic mothers experienced higher rates of neonatal intensive care unit admission and hypoglycemia.
Conclusion
The prevalence of gestational diabetes in the Micronesian population is lower than expected given the high prevalence of obesity and type 2 diabetes among Micronesians. Those with gestational diabetes are at an increased risk for maternal and neonatal morbidity. Future public health endeavors should address increasing rates of obesity in the United States, specifically in Pacific Islander populations.
Introduction
Gestational diabetes, defined as glucose intolerance with onset or first recognition during pregnancy, complicates 2–7% of all pregnancies in the United States.1,2 Prevalence rates have been noted to vary greatly between ethnic and racial groups. Estimates of type 2 diabetes among individuals of Micronesian ancestry range between 20 and 41%.3 Because of this markedly elevated rate compared to other groups, it has been assumed that Micronesians are also at increased risk for gestational diabetes. The true prevalence of gestational diabetes in this population, however, is unknown.
The primary objective of this study was to determine the prevalence of gestational diabetes in women of Micronesian ancestry residing in Hawai‘i. Secondary objectives were to determine maternal characteristics associated with the presence of gestational diabetes and to compare maternal and fetal outcomes between the gestational diabetic and non-diabetic populations.
Methods
A retrospective chart review was performed of all delivery records from January 1997 to December 2006 at Kapi‘olani Medical Center for Women and Children (KMCWC). KMCWC is located in Honolulu, Hawai‘i. It has the largest obstetric unit in the state and does approximately 6,000 deliveries per year. All individuals admitted to KMCWC are asked to self identify their race and ethnicity. Women were initially included in this study if they listed themselves in the category of “Other Pacific Islander, “ (non-Hawaiian, non-Samoan”) and had a singleton birth at more than 20 weeks gestation during the study period. The charts of subjects potentially meeting inclusion criteria were reviewed. At time of triage intake, the nurses recorded patients' ethnicities; upon review of the intake, additional patients were excluded if their ethnicities were not Micronesian, e.g. Tongan.
Information on the screening and diagnosis of gestational diabetes as well as maternal and neonatal outcomes were obtained utilizing the patient's delivery record, prenatal record, one-hour glucose tolerance test, and three-hour glucose tolerance test if it was performed. Using definitions established by the American College of Obstetricians and Gynecologists (ACOG), gestational diabetes was designated when the study subject had two or more elevated glucose levels on the three-hour glucose tolerance test.2 Those subjects unscreened for gestational diabetes were included in the non-diabetic group for the data analysis. Subjects with type 2 diabetes which preceded pregnancy (pre-gestational diabetes) were identified by an ICD-9 code for type 2 diabetes and confirmed by chart review. These patients with pre-existing diabetes were excluded from the data analysis.
Body mass index (BMI) was calculated using the patient's height and pre-gestational weight recorded by the nurse at time of intake. Of note, the height and weight were not measured at time of intake; rather, they were obtained from the pre-natal record or by the patient's self-report if the pre-natal record was not available. Mode of delivery, fetal weight, Apgar scores, and gestational age at delivery were obtained from the delivery records. Other maternal and fetal outcomes (hypertensive disease, maternal infection, shoulder dystocia, neonatal intensive care/special care unit admission, and neonatal hypoglycemia) were identified by their respective ICD-9 codes and confirmed by chart review.
Measures of association including chi-square, t-tests and multiple logistic regression were used to analyze differences in demographics and maternal outcomes and fetal outcomes between the gestational diabetic and non-diabetic populations. Analysis was performed using SPSS version 16.0 (Chicago, Illinois). This study was approved by the Hawaii Pacific Health Institutional Review Board.
Results
Out of the 2966 charts of persons classified as “Other Pacific Islander” that initially reviewed, 2303 subjects met inclusion criteria as being Micronesian and having a singleton birth at more than 20 weeks gestation. There were 19 subjects (0.8%) who had a diagnosis of type 2 diabetes prior to pregnancy. After excluding these 19 subjects, 1999 (87.5%) were properly screened for gestational diabetes. An additional 27 subjects (1.2%) had an elevated onehour glucose tolerance test but never completed screening with the three-hour glucose tolerance test. There were 258 subjects (11.3%) who were not screened for gestational diabetes. Rates of diabetes and pre-gestational diabetes for the study population are presented in Table 1. The prevalence of gestational diabetes in Micronesian patients was 6.2%.
Table 1.
Prevalence of Pre-gestational and Gestational Diabetes
| Number (%) | ||
| Total Study Population | 2303 (100.0) | |
| Non-diabetic | 2,141 (93.0) | |
| Pre-gestational diabetic | 19 (0.8) | |
| Gestational diabetic | 143 (6.2) | |
| Diet-controlled | 90 (3.9) | |
| Medication-controlled | 53 (2.3) | |
Characteristics of the population are described in Table 2. The mean pre-pregnancy BMI of the gestational diabetic group was 36.5 versus 31.2 in the non-diabetic group (p < 0.001). Of note, both groups had a mean body mass index (BMI) in the obese range. There was no difference in weight gain during pregnancy among the two groups. With a mean age of 30.2 versus 25.2 in the non-diabetic group, the gestational diabetic subjects were more likely to be older (p = 0.002).
Table 2.
Maternal Characteristics
| Mean (sd) | Non-Diabetic Mean (sd) | Gestational Diabetic Mean (sd) | p-value |
| Age in years | 25.2 (5.1) | 30.2 (6.0) | 0.002 |
| BMI in kg/m2 | 31.2 (7.0) | 36.5 (7.0) | <0.001 |
| Weight gain in pounds | 30.7 (17.7) | 31.5 (24.4) | 0.617 |
| Parity | 1.6 (1.7) | 2.0 (2.1) | 0.002 |
Multiple regression analysis was then performed. After controlling for age and parity, obese Micronesian women had a 4.1 fold greater risk of developing gestational diabetes compared to their non-obese counterparts (95% CI 2.39–7.04).
Maternal Outcomes
The maternal outcomes for the study population are described in Table 3. Cesarean section rates were higher in the gestational diabetic group compared to the non-diabetic group. After controlling for age, BMI, and parity, a gestational diabetic Micronesian woman had a 1.8 fold greater risk of having a cesarean section when compared with her non-diabetic counterpart (95% CI 1.21–2.74). However, there was no significant difference in operative vaginal delivery rates. The gestational diabetic population experienced higher rates of hypertensive diseases compared to the non-diabetic population (16.8% versus 6.0%, p < 0.001). Rates of shoulder dystocia in the gestational diabetic population were higher than in the non-diabetic population (2.1% versus 1.2%), however this difference was not statistically significant.
Table 3.
Maternal Outcomes
| Non-Diabetic (%) | Gestational Diabetic (%) | p-value | |
| Cesarean section | 17.4 | 35.3 | <0.001 |
| Hypertensive diseases | 6.0 | 16.8 | <0.001 |
| Shoulder dystocia | 1.2 | 2.1 | 0.361 |
| Operative delivery | 10.2 | 6.5 | 0.247 |
| Maternal infection | 6.8 | 5.6 | 0.585 |
Neonatal Outcomes
Neonatal outcomes are presented in Table 4. Birth weight in the gestational diabetic group was significantly higher (3421 grams versus 3224 grams, p < 0.001). Admission to special care and neonatal intensive care units were also significantly higher for infants of gestational diabetic mothers compared to babies of non-diabetic mothers (21.7% versus 7.8%, p < 0.001). Similarly, infants of gestational diabetic mothers also experienced higher rates of hypoglycemia (4.9% versus 2.0, p = 0.019). There were no differences in Apgar scores, gestational age at delivery, and preterm delivery rates between groups.
Table 4.
Neonatal Outcomes
| Non-diabetic | Gestational diabetic | p-value | |
| Weight in grams | 3224(sd 548) | 3421 (sd 666) | <0.001 |
| Special care/NICU admit | 7.8 % | 21.7 % | <0.001 |
| Hypoglycemia | 2.0 % | 4.9 % | 0.019 |
| Age at delivery in weeks | 38.3 (sd 3.9) | 37.7 (sd 2.0) | 0.061 |
Discussion
To our knowledge, this is the first study to examine the prevalence of gestational diabetes among Micronesian women living in the United States. Previous studies have calculated the rates of gestational diabetes in Pacific Island populations. In 2006, Silva et al. determined a prevalence of 3.6% for the Native Hawaiian and Pacific Islander population in Hawai‘i.4 In a retrospective study examining perinatal outcomes between Asian Americans and Pacific Islanders, Rao et al reported the rate of gestational diabetes as 7.2% for Pacific Islanders.5 A recent retrospective study calculating the prevalence of gestational diabetes among Asian and Pacific Islander subgroups in the United States estimated a prevalence of 5.82% for US-born Pacific Islanders and 8.38% for foreign-born Pacific Islanders.6 Historically, if Micronesians were included in the analysis, they were grouped in the Asian and Pacific Islander category or the Pacific Islander subgroup, both of which include many diverse populations.
Because it has been shown that the prevalence of type 2 diabetes among Micronesians is higher than in other populations,3 it was assumed that Micronesians would also have a higher prevalence of gestational diabetes. However, we found the prevalences of gestational diabetes and pre-gestational diabetes, which in this study were 6.2% and 0.8%, respectively, to be lower than recently calculated prevalences for the general population. A recent study of 209,287 patients who delivered from 1999 through 2005 in Kaiser Permanente hospitals in southern California reported a prevalence of pre-gestational diabetes of 1.3% and gestational diabetes of 7.6%.7 The relatively low prevalence of gestational and type 2 diabetes in our study may be in part attributed to insufficient screening for diabetes during pregnancy and prior to pregnancy as well. Since 13.5% of our subjects were not screened in accordance with ACOG recommendations, this could have falsely lowered our diabetes rates.
The strong association between obesity and both pre-gestational and gestational diabetes is well established. Thus, it is even more surprising that the calculated rates of pre-gestational and gestational diabetes in our study population were lower than expected when taking into consideration that the mean BMI of both the non-diabetic and gestational diabetic groups fell in the obese range. Since obesity also contributes to other maternal complications of pregnancy as well as the development of diabetes and cardiovascular disease, this study highlights the need for weight loss intervention and management in this population.
Although a number of studies have documented that self-reported weight and height is an accurate representation of a woman's body mass index,8–10 the validity of this information is a limitation of this study. Because women of all weights tend to underestimate their weight and over estimate their height, this type of exposure misclassifi cation would be non-differential and may actually underestimate the high obesity rates.8–10
Gestational diabetes has been shown to increase maternal and neonatal morbidity, and this was noted in our study as well. The clinically significant but not statistically significant difference in shoulder dystocia rates is likely secondary to the low incidence of shoulder dystocia. Both groups had mean fetal weights that were not in the range of macrosomia (> 4,000 grams) but the larger mean fetal weight in the gestational diabetes group likely contributed to the higher rates of cesarean delivery.
Honolulu's hospitals are providing health care for a growing number of Micronesian patients. This study highlights the importance of providing them with comprehensive postpartum and primary care. For example, more effort should be made to have our patients undergo a two-hour glucose tolerance test six weeks postpartum to determine if they have type 2 diabetes versus gestational diabetes. The study population had a relatively low prevalence of type 2 diabetes. But they are at significantly higher risk then the general population of developing type 2 diabetes in their lifetime. Pregnancy is thus an ideal time to initiate interventions such as weight loss and management that will decrease the risk for diabetes in this obese population. As their care is often complicated by language, cultural, and financial barriers, more studies need to be performed to better understand their health needs and to design interventions that will improve their health outcomes.
Footnotes
Source of support: none
No potential conflicts of interest relevant to this article were reported.
References
- 1.Jovanovic L, Pettitt DJ. Gestational diabetes mellitus. JAMA. 2001 Nov 28;286(20):2516–2518. doi: 10.1001/jama.286.20.2516. [DOI] [PubMed] [Google Scholar]
- 2.ACOG Practice Bulletin. Clinical management guidelines for obstetrician-gynecologists. Number 30, September 2001 (replaces Technical Bulletin Number 200, December 1994). Gestational diabetes. Obstet Gynecol. 2001 Sep;98(3):525–538. [PubMed] [Google Scholar]
- 3.King H, Rewers M. Global estimates for prevalence of diabetes mellitus and impaired glucose tolerance in adults. WHO Ad Hoc Diabetes Reporting Group. Diabetes Care. 1993 Jan;16(1):157–177. doi: 10.2337/diacare.16.1.157. [DOI] [PubMed] [Google Scholar]
- 4.Silva JK, Kaholokula JK, Ratner R, Mau M. Ethnic differences in perinatal outcome of gestational diabetes mellitus. Diabetes Care. 2006 Sep;29(9):2058–2063. doi: 10.2337/dc06-0458. [DOI] [PubMed] [Google Scholar]
- 5.Rao AK, Daniels K, El-Sayed YY, Moshesh MK, Caughey AB. Perinatal outcomes among Asian American and Pacific Islander women. Am J Obstet Gynecol. 2006 Sep;195(3):834–838. doi: 10.1016/j.ajog.2006.06.079. [DOI] [PubMed] [Google Scholar]
- 6.Chu SY, Abe K, Hall LR, Kim SY, Njoroge T, Qin C. Gestational diabetes mellitus: all Asians are not alike. Prev Med. 2009 Jul; doi: 10.1016/j.ypmed.2009.07.001. (Epub ahead of print) [DOI] [PubMed] [Google Scholar]
- 7.Lawrence JM, Contreras R, Chen W, Sacks DA. Trends in the prevalence of preexisting diabetes and gestational diabetes mellitus among a racially/ethnically diverse population of pregnant women, 1999–2005. Diabetes Care. 2008 May;31(5):899–904. doi: 10.2337/dc07-2345. [DOI] [PubMed] [Google Scholar]
- 8.Le Marchand L, Yoshizawa CN, Nomura AM. Validation of body size information on driver's licenses. Am J Epidemiol. 1988 Oct;128(4):874–877. doi: 10.1093/oxfordjournals.aje.a115040. [DOI] [PubMed] [Google Scholar]
- 9.Stewart AW, JR, Ford MA, Beaglehole R. Underestimation of relative weight by use of self reported height and weight. Am J Epidemiol. 1987;125(1):122–126. doi: 10.1093/oxfordjournals.aje.a114494. 1987. [DOI] [PubMed] [Google Scholar]
- 10.Palta M PR, Berman R, Hannan P. Comparisons of self-reported and measured height and weight. Am J Epidemiol. 1982;115(1):122–126. doi: 10.1093/oxfordjournals.aje.a113294. 1982. [DOI] [PubMed] [Google Scholar]