Relationships Between Early Nutrition and Blood Glucose Concentrations in Very Preterm Infants

The aim of the study was to determine whether changes to early nutrition are associated with levels of glycemia in very preterm infants.

A retrospective, observational study of infants <1500 g or <30 weeks' gestation admitted to Neonatal Intensive Care, National Women's Hospital, New Zealand, before (Old Protocol) and after (New Protocol) a change in nutritional protocol. Nutritional intakes were calculated and averaged by day for postnatal days 1 to 7 (week 1) and 1 to 28 (month 1). Relationships between glycemia measures, macronutrient intakes, and achievement of 10% enteral feeds (≥10% total intake) were explored using logistic regression.

Old Protocol (n = 190) and New Protocol (n = 267) groups had similar baseline characteristics. In week 1, New Protocol infants received more protein, less fat, and carbohydrate, had lower mean blood glucose concentrations (BGCs) (mean ± SD 4.9 ± 1.2 vs 5.6 ± 1.4 mmoll/L, P < 0.0001), less hyperglycemia (BGC > 8.5 mmol/L, 71 [27%] vs 80 [42%], P = 0.0005), but similar hypoglycemia (BGC < 2.6). In month 1, New Protocol infants also had less hyperglycemia (105 [39%] vs 96 [51%], P = 0.02) and lower mean BGC (5.0 ± 1.1 vs 5.5 ± 1.1 mmol/L, P < 0.0001), but insulin usage was similar. After adjustment for birth weight z score and gestational age, hyperglycemia was significantly associated with week 1 intakes (g · kg · day) of protein (odds ratio [95% confidence intervals] 0.47 [0.23-0.79], P = 0.004), fat (0.54 [0.40-0.74], P < 0.0001), and carbohydrate (1.25 [1.09-1.44], P < 0.0001). These relationships were similar for month 1. Each additional day to achieve 10% enteral feeds was associated with increased odds of hypoglycemia (1.09 [1.00-1.18], P = 0.04) and hyperglycemia (1.16 [1.06-1.28], P = 0.002).

In very preterm infants, macronutrient balance and small, early enteral feeds may assist glycemic control.