Associations Between Carbohydrate Intake Behaviours and Glycaemia in Gestational Diabetes: A Prospective Observational Study

Carbohydrate intake (CI) has the largest impact on the short-term glycaemia of all nutrients, yet optimal CI management in gestational diabetes remains unclear. Objective: To examine CI behaviours in individuals with recently diagnosed gestational diabetes and their association with self-monitored blood glucose. Methods: Data from 97 individuals were collected using food and blood glucose diaries. CI (including amounts, types, and timing) was manually assessed using 15 g servings over 5-8 days, while a 3-day computerised analysis examined a broader intake of macro- and micronutrients. Results: Elevated fasting glycaemia (EFG) was associated with lower total CI (Mdn 10.8 vs. 12.5 servings/day, p = 0.006), missed meals (Mdn 1.4 vs. 0.0/week, p = 0.007), missed snacks (Mdn 10.5 vs. 7.5/week, p = 0.038), low-carbohydrate meals (<30 g; Mdn 4.3 vs. 2.0/week, p = 0.004), and a higher proportion of energy intake from fat (Mdn 35% vs. 33%, p = 0.047), as compared with in-target fasting glycaemia. In contrast, elevated postprandial glycaemia (EPG) was not significantly associated with total CI, low-carbohydrate meals (<30 g), low-carbohydrate snacks (<15 g), or high-carbohydrate loads (>50 g). EPG was instead associated with high-glycaemic index meals (Mdn 1.6 vs. 0.9 lunch meals/week, p = 0.026; Mdn 0.9 vs. 0.0 dinner meals/week, p = 0.023); and a lower intake of energy (Mdn 7650 kJ vs. 9070 kJ/day, p = 0.031), protein (Mdn 91 g vs. 109 g/day, p = 0.015), fat (Mdn 61 g vs. 84 g/day, p = 0.003), and multiple micronutrients (p <0.05), as compared with in-target postprandial glycaemia. Conclusions: CI profiles differed for individuals with EFG, as compared with EPG, emphasising the need for dietary guidelines tailored for gestational diabetes subtypes. Further interventional studies are needed to explore these findings, particularly the associations between EFG and low CI behaviours.