Rationale for Insulin Management in Gestational Diabetes Mellitus ODED LANGER, MICHAEL BERKUS, LOIS BRUSTMAN, AKOLISA ANYAEGBUNAM, AND ROGER MAZZE

A prospective study was undertaken to test the hypothesis that insulin treatment in patients with gestational diabetes mellitus (GDM) with fasting plasma glucose (FPG) >5.3 mM significantly reduces adverse perinatal outcome. Assigned to insulin or diet treatment based on FPG were 471 GDM women. Four factors believed to be associated with infants large for gestational age (LGA) were evaluated: FPG, overall glycemic control, maternal weight, and treatment regimen. We found that when glycemic control was optimized, the key factors related to large infants were FPG and treatment modality. In the low-FPG group (5.3 mM can be the basis for initiation of insulin treatment in GDM subjects with optimization of glycemic control as the goal. This approach may contribute significantly to reduced neonatal risk and may foster a standardized method for rapid and effective assignment to treatment. Diabetes 40 (Suppl. 2): 186-90, 1991

T

oday, the rationale for the treatment of gestational diabetes mellitus (GDM) is prevention of two major complications: stillbirth and macrosomia. Both complications are related to maternal glycemic control. Additionally, treatment concentrates on prevention of macrosomia-related morbidity. Although, in the last decade, perinatal mortality has dropped to approximately the rate in the nondiabetic population (1-4), the incidence of macrosomia remains unchanged: 20-50% (2,3,5-7). The failure to significantly effect the reduction of macrosomia

186

may be because of inadequate knowledge of a management rationale. The First (1980) and Second (1985) International Workshop-Conferences on GDM recommended initiation of insulin when fasting plasma glucose (FPG) was >5.8 mM and/or the 2-h postprandial plasma glucose was >6.7 mM (8,9). This recommendation was supported by the American College of Obstetricians and Gynecologists (10). Despite these recommendations, lack of uniformity persists in the insulininitiation criteria in the management of the GDM patient. In a survey researching the management approaches of maternal-fetal medicine specialists in the United States, the results showed that inconsistency exists in the criteria for insulin initiation. Forty-six percent of the specialists used an FPG cutoff either 5.8 mM (ranging from 6.2 to 8.4). Only 22% of the sample respondents initiated insulin therapy with the recommended 2-h postprandial glucose threshold (6.7 mM), and 78% used values ranging from 6.7 to 10.0 mM (11). Insulin initiation depends on determining the level of blood glucose after diet therapy has failed. For diet-treated subjects, consensus is lacking among practitioners on how long to wait or at what precise level of glucose control insulin should augment diet therapy or what specific diet to use. Because of inconsistent guidelines, depending on the medical center, the woman with GDM may receive insulin therapy after several days or weeks of diet treatment. This wait-and-see approach may seriously hamper rapid achievement of optimized metabolic control for subjects whose improved glycemia could not adequately be obtained by diet alone. Consequently, a high incidence of large for gestational age (LGA) infants may result. Because fasting plasma glucose is considered an accu-

From the Departments of Obstetrics and Gynecology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas; and Albert Einstein College of Medicine, Bronx, New York. Address correspondence and reprint requests to Oded Langer, MD, Department of Obstetrics and Gynecology, UTHSCSA, 7703 Floyd Curl Drive, San Antonio, TX 78284-7836.

DIABETES, VOL. 40, SUPPL 2, DECEMBER 1991

O. LANGER AND ASSOCIATES

rate reflection of metabolic abnormalities, we sought to test the hypothesis that insulin treatment in GDM patients with fasting plasma glucose >5.3 mM significantly reduces adverse perinatal outcome. The rationale for this glucose threshold is founded on the results of our previous studies that disclosed a mean ± SD fasting blood glucose of 4.8 ± 0.5 in nondiabetic individuals. In addition, we found that GDM subjects with FPG >5.3 mM had impaired insulin secretion (12,13).

RESEARCH DESIGN AND METHODS

Participants in the study were 471 women diagnosed as GDM by 100-g 3-h oral glucose tolerance test (OGTT) with the National Diabetes Data Group criteria (14). To assure consistency in testing procedure, all women were instructed to add 150 g of carbohydrate to their usual meals for each of 3 days before the test and to fast for 12 h (overnight) before the OGTT. Within 5 days after the OGTT, women were assigned to diet or insulin therapy based on two determinations of fasting plasma glucose levels. Insulin treatment was initiated for all patients with FPG > 5.88 mM. In those women with an FPG < 5.8 mM, diet treatment was initiated. For the latter group, change from diet to insulin required seven consecutive days in which optimized control could not be achieved. Obesity was defined as prepregnancy body mass index (BMI) > 27 kg/m2. For dietary treatment, obese subjects were prescribed 25 kcal • kg~ 1 and lean subjects were prescribed 30 kcal k g " 1 for their current pregnant weight. Meals were subdivided into seven segments (3 meals and 4 snacks) and contained - 5 0 % carbohydrate, - 3 0 % fat, and - 2 0 % protein. Insulin therapy consisted of three injections/ day (regular and NPH before breakfast, regular at dinner, and NPH at bedtime). The initial total insulin dose was calculated based on 0.7 U • k g " 1 for current body weight proportioned 2:1 moming:evening (with morning dose 2:1 NPH:regular and evening dose 1:1 regulanNPH) (15). All patients were placed on memory-based reflectance meters to ensure collection of accurate and reliable ambulatory blood glucose values (16). The patients were instructed by nurse educators and nutritionists in selfmonitoring of blood glucose (7 times/day: fasting pre- and 2-h postprandial and bedtime), diet calculation, and insulin administration. Compliance with diet and insulin regimens was assessed by examination of the glucose data stored in the memory reflectance meters. Optimized metabolic control (fasting blood plasma 120 mg/dl. The rest of the gestational diabetes mellitus (GDM) subjects were assigned to diet group. In this group, 53% required insulin to improve glycemic control. For analysis, low-FPG (

Rationale for insulin management in gestational diabetes mellitus.

A prospective study was undertaken to test the hypothesis that insulin treatment in patients with gestational diabetes mellitus (GDM) with fasting pla...
847KB Sizes 0 Downloads 0 Views