GDM: Carbohydrate (2001)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
A description of intensive nutrition therapy for gestational diabetes mellitus along with recommendations for future research is described.
Inclusion Criteria:

Article inclusion criteria not described.

Exclusion Criteria:
Not described.
Description of Study Protocol:

Recruitment

Article selection methods not described.

Design

Narrative Review.

Blinding Used (if applicable):  not applicable

Intervention (if applicable):  not applicable

Statistical Analysis

Not applicable.

Data Collection Summary:

Timing of Measurements:

Not applicable.

Dependent Variables:

Not applicable.

Independent Variables:

Not applicable.

Control Variables:

Not applicable.

Description of Actual Data Sample:

Initial N:  51 references included.

Attrition (Final N):  51

Age:  Not applicable

Ethnicity:  Not applicable

Other Relevant Demographics:

Anthropometrics:

Location:  Worldwide studies

Summary of Results:

Definitions:

Intensive nutrition therapy for GDM refers to the controlled intake of total amount, type, and distribution of carbohydrates while providing adequate calories.

Intensive nutrition therapy in combination with daily self-blood-glucose monitoring (SBGM) has not been explored as a viable alternative to insulin therapy.

Caloric restriction of obese women:

1. Moderate kcal restriction (1,700 – 1,800 kcal/d, 25 kcal/kg prepregnancy DBW)

Moderate restriction of kcal resulted in lower weight gain although average infant birthweights were still 500 g higher than infants of nonobese women.

2. Severe kcal restriction (1,200 kcal/d)

Moderate kcal restriction appears to be less likely to result in ketonuria, reduce rates of macrosomia, and not have adverse neonatal outcomes.

Severe kcal restriction improves glycemic control but leads to ketonemia and ketonuria (the effects of ketones on the developing fetus are unknown).

Low average blood glucose during pregnancy has been associated with an increased incidence of SGA infants.

Nutrition therapy and the need for insulin:

Studies comparing perinatal outcomes in women treated with insulin compared with those treated only by diet.

Limitations of these studies include insufficient information about the dietary therapy, lack of evaluation of the effectiveness of the dietary therapy in achieving normoglycemia and less intensive use of SBGM for women treated with diet alone.

Sweet Success Diabetes and Pregnancy Program at Children’s Hospital, San Francisco evaluated intensive nutrition therapy.

The frequency of LGA infants reported in this study (4 x daily, SBGM was used in both groups) was 11.5% for the diet-only group and 23.7% for the insulin added group.

30% of the women in this group required insulin (these women also weighed more).

Costs of insulin therapy:

The cost of insulin therapy for gestational diabetes increases the cost of care.  The cost-effectiveness of intensive nutrition therapy for GDM needs to be evaluated for its influence on the frequency of insulin therapy.

Role of SBGM:

1.        Currently, consensus on the use of SBGM exists only for women requiring insulin during pregnancy. 

2.        Daily fasting and postprandial SBGM may improve perinatal outcomes. 

Fewer macrosomic infants were born to insulin-treated GDM women who tested 1-h postprandial blood glucose levels as compared with another group who tested preprandial levels.

Women with GDM were randomized to either the conventional management group or the intensive group (SBGM 7 x/d).  The intensive group had lower rates of LGA infants in both the insulin-treated and the diet-treated women.

Meal Patterns and Blood Glucose Control:

Optimal meal pattern for the treatment of GDM remains controversial.

Test diet of 3 meals/d compared with hourly feedings:

Mean serum insulin was decreased 28% and C-peptide output decreased by 20% for the “nibbling” group.

Meal patterns may be 3 meals + 3 snacks or 3 meals + an evening snack.

Rationale for intensive nutrition therapy:  Pregnancy metabolism

Decreased sensitivity to insulin by mid pregnancy because of the increased levels of human placental lactogen, serum cortisol, progesterone, and estrogen. 

Women who develop GDM are unable to secrete enough insulin or not enough is secreted when needed.

Blood glucose is most difficult to control after the first meal of the day because of peak levels of cortisol between 3 and 9 a.m.

Intensive Nutrition Therapy for GDM

Limitation of total carbohydrate and careful distribution of carbohydrate throughout the day at several meals and snacks is the strategy to achieve normal blood glucose levels. This is designed to: prevent hyperglycemia, meet the metabolic need for fuels of the pregnant woman and prevent starvation ketosis.

Nutrition therapy for the late third trimester may require very intensive nutrition therapy as gestational diabetes results in worsening glucose tolerance as gestation progresses.

The decision to begin insulin therapy is based on clinical indexes, SBGM, and dietary intake information.

Summary of intensive nutritional treatment for GDM:

Meal pattern:

Three meals plus three or  more snacks (2 to 3 hr intervals)

Diet composition:

Nutrition and exercise only (no insulin)

38-45 % complex carbohydrates (high fiber)

20-25% protein

30-40% fat (mono and PUFA preferred)

 Energy levels:

Second trimester: 25-30 kcal/kg IBW

Third trimester: 30-35 kcal/kg IBW

(prepregnancy weight)

Weight gain based on prepregnancy weight.

1.  Daily SBGM:Peak (1-hr) after meals and fasting

2.  Adequacy of kcal and carbohydrates to prevent ketonuria and promote recommended weight gain.

3.  Adequacy of blood glucose control based on SBGM and daily food records.

4.  Insulin therapy: based on weight, blood glucose control, urinary ketones, adequacy of dietary intake and adherence to nutrition plan.

Author Conclusion:

Intensive nutrition therapy is potentially important in the management of GDM. Few studies have evaluated the efficacy of intensive nutrition therapy in the treatment of GDM.

Frequent daily SBGM is an essential adjunct to intensive nutrition therapy for women with GDM and allows the woman to adjust diet to bring blood glucose under control and reinforces dietary management principles.

Future research should evaluate the benefit of intensified nutrition therapy on perinatal outcomes and to eliminate the need for insulin for treating GDM.

Funding Source:
University/Hospital: University of California Berkeley, Children's Hospital
Reviewer Comments:

This is a nice review of the current literature but does not critically analyze the studies discussed.

Quality Criteria Checklist: Review Articles
Relevance Questions
  1. Will the answer if true, have a direct bearing on the health of patients? Yes
  2. Is the outcome or topic something that patients/clients/population groups would care about? Yes
  3. Is the problem addressed in the review one that is relevant to dietetics practice? Yes
  4. Will the information, if true, require a change in practice? Yes
 
Validity Questions
  1. Was the question for the review clearly focused and appropriate? Yes
  2. Was the search strategy used to locate relevant studies comprehensive? Were the databases searched and the search termsused described? No
  3. Were explicit methods used to select studies to include in the review? Were inclusion/exclusion criteria specified andappropriate? Wereselectionmethods unbiased? ???
  4. Was there an appraisal of the quality and validity of studies included in the review? Were appraisal methodsspecified,appropriate, andreproducible? No
  5. Were specific treatments/interventions/exposures described? Were treatments similar enough to be combined? ???
  6. Was the outcome of interest clearly indicated? Were other potential harms and benefits considered? Yes
  7. Were processes for data abstraction, synthesis, and analysis described? Were they applied consistently acrossstudies and groups? Was thereappropriate use of qualitative and/or quantitative synthesis? Was variation in findings among studies analyzed? Were heterogeneity issued considered? If data from studies were aggregated for meta-analysis, was the procedure described? No
  8. Are the results clearly presented in narrative and/or quantitative terms? If summary statistics are used, are levels ofsignificance and/or confidence intervals included? Yes
  9. Are conclusions supported by results with biases and limitations taken into consideration? Are limitations ofthe review identified anddiscussed? Yes
  10. Was bias due to the review's funding or sponsorship unlikely? Yes