Abstract:
Aim: To investigate the effect of different bedtime snacks (higher carbohydrate versus lower carbohydrate versus no snack) on first morning fasting blood glucose levels (BGLs) in women with diet-controlled gestational diabetes mellitus (GDM) and borderline fasting glucose levels.
Methods: This prospective randomised crossover trial enrolled 82 women with diet controlled GDM. To be eligible women had to be diagnosed with GDM on a routine oral glucose tolerance test (OGTT) according to standard IADPSG criteria or diagnostic fasting BGL, be 18 years or older and have a singleton pregnancy between 24- and 34-weeks' gestation. They needed to have two or more first morning fasting BGLs between 4.7 and 5.4 mmol/L in the week prior to recruitment. The women were randomly allocated to 6 different orders of bedtime snacks for 5 days each in the total 15-day study period. The snacks comprised a higher carbohydrate snack (small traditional plain yoghurt tub and a small-medium apple, providing 220 calories, 25g carbohydrate, 10g protein, 7.7g fat and 3.3g fibre), a lower carbohydrate snack (10 almonds and 20g of dark chocolate, providing 184 calories, 7.4g carbohydrate, 4.2g protein,14.8g fat and 1.1g fibre) and no bedtime snack. The primary outcome was fasting capillary BGL as measured with a home glucometer, and the secondary outcome was requirement for insulin as assessed by a physician.
Results: A total of 68 women with GDM were enrolled and completed the study at a median gestation of 30.8 weeks. Compared with no bedtime snack, the higher carbohydrate snack (4.96 vs 4.87 mmol/L, mean difference: 0.09 mmol/L, 95% CI 0.05-0.13, p<0.001) and the lower carbohydrate snack (5.01 vs 4.87 mmol/L, mean difference: 0.14 mmol/L, 95% CI 0.09-0.18, p<0.001) were both associated with a slightly higher fasting BGL the following morning.
Conclusions: Taking a bedtime snack was associated with slightly higher fasting BGLs in women with diet controlled GDM compared with no bedtime snack. (Clinical trial registration: ACTRN12617000659303).
Keywords:
gestational diabetes mellitus, blood glucose, fasting, snacks, medical nutrition therapy