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The purpose of this review is to evaluate original research addressing criteria for insulin management in gestational diabetes.

Research spanning the 20 years prior to this review.

None stated.

Recruitment:

Original studies spanning the past 20 years prior to this review.

Design:

Narrative Review.

Blinding Used (if applicable):

Not applicable.

Intervention (if applicable):

Not applicable.

Statistical Analysis: 

Not applicable.

Timing of Measurements:

Not applicable

Dependent Variables:

Not applicable

Independent Variables:

Not applicable

Control Variables: 

Not applicable

Initial N: 58 studies

Attrition: (Final N):  58

Age:  Not stated

Ethnicity:  Not stated

Other Relevant Demographics:  Not stated

Anthropometrics:  Not stated

Location:  Worldwide studies

Other Findings

It is recommended that patients with fasting plasma glucose on the OGTT of <96 mg/dl be assigned to diet therapy and obese women or those with fasting plasma glucose >95 mg/dl on the OGTT be referred for insulin therapy to minimize exposure of the fetus to a hyperglycemic environment.

Studies of women with GDM have shown that macrosomia (birthweight >4000 g) ranges from 7% to 33% and infants large for gestational age (>90^th %) ranges from 10% to 47%.

In a large study of patients with GDM, the author demonstrated that when the mean blood glucose level was >105 mg/dl, there was a greater risk for the development of large for gestational age infants.  Also, untreated GDM results in an increased incidence of macrosomia, respiratory distress syndrome, and other abnormalities of fetal metabolism.

Insulin is recommended when standard dietary management does not consistently maintain fasting plasma glucose at <105 mg/dl or the 2-hr postprandial plasma glucose at <120 mg/dl.

In a study by the author, 38% of GDM patients required insulin therapy and of the remaining 62% assigned to diet therapy (plasma glucose <105 mg/dl), 50% failed to achieve near-normoglycemic levels of control with SMBG using memory reflectance meters. This resulted in ~60% of the study population being treated with insulin.

In a 4-wk prospective study by the author, patients with GDM were grouped based on fasting plasma glucose (<95 mg/dl and >95 mg/dl).  In the <95 mg/dl group, 70% achieved good control within the first 2 wk of the study.  In the group >95 mg/dl, only 30% of the cases achieved good control.

A requirement for effective insulin therapy is self-monitoring of blood glucose (SBGM) be performed frequently each day. The use of a memory reflectance meter is the most effective tool in monitoring blood glucose levels over time.

Despite the recommendations for SBGM, only 39% of the maternal/fetal sub specialists in a 1990 survey reported following this recommendation. Of these sub specialists, 52% used weekly management of fasting glucose alone or fasting and postprandial glucose as the method to evaluate glycemic control in spite of the fact that weekly blood glucose measurements are inadequate to prevent macrosomia compared to SBGM.

In a 1995 survey of GDM, it was found that 20% of the diet patients, 63% of patients receiving single doses of insulin and 85% of those on split-dose insulin performed daily SMBG. 

Nonobese patients with fasting plasma glucose on the OGTT of <96 mg/dl should be referred for diet therapy. In obese women or those with fasting plasma >95 mg/dl on the OGTT, insulin therapy can be initiated immediately to avoid exposing the fetus to a hyperglycemic environment. This in conjunction with patient education on the importance of glycemic control improves patient compliance that in turn optimizes the management approach.

University/Hospital:

University of Texas Health Science Center

RD’s working with women who have GDM should monitor SBGM records and recommend the initiation of insulin when blood glucose goals are not being met.