Prescribing exercise for prevention and treatment of gestational diabetes: review of suggested recommendations.

Exercise has been proved to be safe during pregnancy and to offer benefits for both mother and fetus; moreover, physical activity may represent a useful tool for gestational diabetes prevention and treatment. Therefore, all women in uncomplicated pregnancy should be encouraged to engage in physical activity as part of a healthy lifestyle. However, exercise in pregnancy needs a careful medical evaluation to exclude medical or obstetric contraindications to exercise, and an appropriate prescription considering frequency, intensity, type and duration of exercise, to carefully balance between potential benefits and potential harmful effects. Moreover, some precautions related to anatomical and functional adaptations observed during pregnancy should be taken into consideration. This review summarized the suggested recommendations for physical activity among pregnant women with focus on gestational diabetes.

Normal glucose tolerance and gestational diabetes mellitus: what is in between?

OBJECTIVE: The aim of this article was to define the metabolic phenotype of pregnant women with one abnormal value (OAV) during an oral glucose tolerance test (OGTT) and to test whether OAV could be considered metabolically comparable to gestational diabetes mellitus (GDM) or a specific entity between GDM and normal pregnancy. RESEARCH DESIGN AND METHODS: After 100-g 3-h OGTTs, 4,053 pregnant women were classified as having GDM, OAV, or normal glucose tolerance (NGT). Those with OAV were subdivided into three subgroups: fasting hyperglycemia (one abnormal value at fasting during an OGTT), 1-h hyperglycemia (one abnormal value at 1 h during an OGTT [1h-OAV]), or 2- or 3-h hyperglycemia (one abnormal value at 2 or 3 h during an OGTT). As derived from the OGTT, we measured insulin sensitivity (insulin sensitivity index [ISI] Matsuda) and insulin secretion (homeostasis model assessment for the estimation of beta-cell secretion [HOMA-B], first- and second-phase insulin secretion). The product of the first-phase index and the ISI was calculated to obtain the insulin secretion-sensitivity index (ISSI). RESULTS: GDM was diagnosed in 17.9% and OAV in 18.7% of pregnant women; women with GDM and OAV were older and had higher BMI and serum triglyceride levels than those with NGT (all P < 0.05). Women with NGT had the highest ISI followed by those with OAV (-21.7%) and GDM (-32.1%). HOMA-B results were comparable with those for OAV and GDM but significantly (P < 0.01) lower than those for NGT; first- and second-phase insulin secretion appeared progressively reduced from that in women with NGT to that in women with OAV and GDM (P < 0.01). ISSI was higher in women with NGT than in women with either OAV (-34%) or GDM (-51.7%) (P < 0.001). Among OAV subgroups, the 1h-OAV subgroup showed the lowest ISSI (P < 0.05). CONCLUSIONS: OAV and GDM are clinically indistinguishable, and both groups are different from women with NGT. Women with GDM and OAV showed impaired insulin secretion and insulin sensitivity, although these defects are more pronounced in women with GDM. Compared with other OAV subgroups, 1h-OAV could be considered a more severe condition.

Early impairment of beta-cell function and insulin sensitivity characterizes normotolerant Caucasian women with previous gestational diabetes.

BACKGROUND AND AIMS: Women with previous gestational diabetes (pGDM) are at high risk of developing type 2 diabetes mellitus. The aim of this study was to evaluate insulin action and insulin secretion in women with pGDM. METHODS AND RESULTS: One hundred and fifty-three pGDM women and 45 with normal glucose tolerance during pregnancy (controls) were studied 1-3years after delivery. Insulin sensitivity (ISI) and beta-cell secretory capacity (beta-index) were derived from 75-g OGTT. Disposition Index was calculated as the product of beta-index and ISI. One hundred and twenty-two pGDM were normotolerant (NGT) and 31 had impaired glucose regulation (IGR) i.e. impaired glucose tolerance and/or impaired fasting glucose. NGT-pGDM, as compared to controls, had significant impairment in insulin action (ISI: 5.46+/-2.81 vs. 7.38+/-3.68, P<0.01) and insulin secretion (beta-index: 4.68+/-1.01 vs. 5.24+/-0.82 pmol/min/m(2); P<0.01). A further impairment was apparent in IGR-pGDM for beta-index (4.16+/-1.09; P<0.05). The disposition index was reduced in NGT-pGDM as compared to controls (33.9%) and further reduced in IGR-pGDM (28.6%, vs. NGT-pGDM; ANOVA P<0.001). In women of normal weight, ISI and beta-index were significantly (P<0.01) impaired in NGT-pGDM compared to controls and further reduced in IGR-pGDM, although a more pronounced defect in insulin secretion was apparent in these women (beta-index: 4.02+/-0.9; P<0.05). CONCLUSIONS: Normotolerant women with pGDM show both impairment in insulin secretion and action irrespective of body weight. A more pronounced defect in insulin secretion seems to characterize normal weight women while a more prominent defect in insulin action is found in overweight women.

Reference intervals for hemoglobin A1c in pregnant women: data from an Italian multicenter study.

BACKGROUND: The reference intervals for hemoglobin A1c (Hb A1c) in pregnant women without diabetes are not well defined, and few examples of reference intervals established by networks of different laboratories are available. METHODS: Five Italian Diabetic Care Units were involved in the study. Data were collected from 445 pregnant women without diabetes, selected on the basis of glucose challenge test results, and from 384 nonpregnant control women. The Hb A1c measurements were performed with HPLC systems aligned to the Diabetes Control and Complications Trial. Plasma glucose measurements were also performed locally. Both Hb A1c and glucose measurements were harmonized by running appropriate external quality assessment schemes. The reference intervals were calculated in terms of nonparametric 2.5th to 97.5th percentiles with 0.90 confidence intervals. RESULTS: The Hb A1c measurements were reproducible (CV = 2.0%) and accurate [mean (SE) difference from the target values, -0.10 (0.06)%]. Glucose measurements were also reproducible (mean CV = 3.2%) and accurate [difference from the target values, -0.01 (0.04) mmol/L]. To calculate common reference intervals, we merged the data collected in the different centers. The Hb A1c reference intervals were 4.0%-5.5% for pregnant nondiabetic women and 4.8%-6.2% for nonpregnant controls. CONCLUSIONS: Healthy pregnant women have lower Hb A1c concentrations than nonpregnant women. The reference intervals for Hb A1c in pregnant women should therefore be lower than those currently in use.