The hypothesis of this prospective, cohort study is that hyperglycemia, hypoglycemia and unstable glucose levels in the first seven days of life in infants born very preterm and at very low birth weights can harm long-term neurodevelopment. The objective of the study is to investigate the relationship between early neonatal glycemia, neonatal characteristics, and developmental outcomes in preterm infants. All infants born before 32. gestational week or below 1500 g admitted to the neonatal intensive care unit will be included in the study. According to the glucose values, the infants will be divided into the normoglycemic group and the group with disturbed glucose concentration. In the corrected age of two neurodevelopmental outcome will be assessed and categorized as normal, mild, moderate or severe impairment. Since the results of published studies about the effects of asymptomatic neonatal hypoglycemia and hyperglycemia on neurodevelopment are inconsistent, the correlation between early disturbances in glucose levels and neurodevelopmental outcome will be assessed.

All infants born before 32 weeks of gestation or weighing <1500 g and admitted to the Neonatal intensive care unit of the University Hospital Center Rijeka will be included into the study. The investigators will collect data from the neonatal period, including: gestational age, sex, birth weight, Apgar score at 1 and 5 minutes, socioeconomic status and Clinical Risk Index for Babies scoring system (CRIB II). Blood glucose levels will be measured at 3rd, 12th, and 18th hour after birth on the first day of life, and from the 2nd to the 7th day of life blood glucose levels will be measured once a day. According to the blood glucose concentrations infants will be divided into normoglycemic group and group with disturbed glucose concentration. The relationship between glycemia category and 2-year outcomes will be investigated. In the corrected age of two years neurodevelopmental outcome will be assessed. Certified psychologists will assess cognitive, motor and language development with the Bayley Scales of Infant and Toddler Development (Bayley III). Bayley III scales are standardized to a mean (SD) score of 100. Pediatric neurologists or pediatrics will examine the children and will estimate the neuromotor function. Cognitive, motor and language development were considered normal if the composite score on the respective Bayley-III score was ≥mean -1SD; mildly impaired if the score was < -1 SD and ≥ -2 SD; moderately impaired if the score was <-2 SD and ≥3 SD; and severely impaired if the score was < mean -3SD.

Cerebral palsy (CP) was evaluated according to the European Cerebral Palsy Network definition. The severity of CP was classified as mild in children who were able to walk without an aid, moderate in children able to walk with an aid, and severe in children who were unable to walk even with an aid.

Children unable to fixate and follow a light with either eye were considered bilaterally blind. Children registered at low-vision centers without blindness were recorded as having moderate visual impairment. Severe auditory impairment was defined as hearing loss that could not be corrected with a hearing aid and moderate auditory impairment was defined as hearing loss corrected with a hearing aid.

The overall outcome was categorized as normal, mild, moderate or severe impairment. Mild impairment was defined as scores between -1and -2 standard deviations from the mean of any of the Bayley-III scales or mild CP. Moderate impairment was defined as scores between -2and -3 standard deviations from the mean of any of the Bayley-III scales, moderate CP, or moderate visual or hearing impairment. Severe impairment was defined as scores between < mean -3 standard deviations of any of the Bayley-III scales, severe CP, or bilateral blindness or deafness.

Inclusion Criteria:

• infants born weighing <1500 g or at <32 weeks of gestation

Exclusion Criteria:

• infants with significant congenital abnormalities
• infants died before day 7
• infants whose mothers suffer from type 1, type 2 diabetes mellitus or gestational diabetes

We will include all infants born before 32 of weeks gestation or weighing below 1500 g and admitted to the Neonatal intensive care unit (NICU) of University Hospital Center Rijeka. Blood glucose concentrations will be measured and recorded from birth until the end of postnatal day 7. Based on the values of glucose concentrations, infantsi will be categorized as normoglycemic, hypoglycemic, hyperglycemic and unstable. At the age between 22,5 and 26,5 months of corrected age assessment by neurologist and psychologist will be performed.

This study is approved by Ethics Committee of University Hospital Center Rijeka and by the Ethics Committee of University of Rijeka - Faculty of Medicine.