Cohort characteristics
| Characteristic | The entire cohort (n=533) | No hyperglycaemia (n=164) | Hyperglycaemia (n=369) | P value* | Hyperglycaemic infants | P value | |
| No insulin (n=298) | Insulin (n=71) | ||||||
| Perinatal variables | |||||||
| Gestational age, weeks, mean (±SD) | 25.3 (1.1) | 25.9 (0.8) | 25.1 (1.1) | <0.001 | 25.2 (1.1) | 24.5 (0.9) | <0.001 |
| Birth weight z-score, mean (±SD) | −0.80 (1.2) | −0.58 (1.1) | −0.90 (1.3) | 0.005 | −0.89 (1.3) | −0.95 (1.3) | 0.717 |
| Male sex, n (%) | 288 (54.0) | 77 (47.0) | 211 (57.2) | 0.031 | 171 (57.4) | 40 (56.3) | 0.894 |
| Singleton birth, n (%) | 417 (78.2) | 131 (79.9) | 286 (77.5) | 0.571 | 233 (78.2) | 53 (74.6) | 0.529 |
| CRIB score, mean (±SD) | 6.5 (3.7) | 5.1 (3.7) | 7.1 (3.5) | <0.001 | 6.7 (3.5) | 8.7 (3.2) | <0.001 |
| Antenatal steroid treatment, mean no. of doses (±SD) | 1.5 (0.7) | 1.6 (0.7) | 1.5 (0.7) | 0.592 | 1.5 (0.7) | 1.7 (0.6) | 0.045 |
| Neonatal variables | |||||||
| Days with mechanical ventilation treatment, median (range)† | 5 (0–14) | 2 (0–14) | 7 (0–14) | <0.001 | 7 (0–14) | 11 (0–14) | <0.001 |
| Days with steroid treatment, mean (±SD)† | 0.3 (1.5) | 0.1 (0.9) | 0.4 (1.7) | 0.007 | 0.3 (1.4) | 1.1 (2.3) | 0.008 |
| Sepsis episodes, median (range)† | 0 (0–3) | 0 (0–2) | 0 (0–3) | 0.467 | 0 (0–3) | 0 (0–2) | 0.959 |
| IVH grade 3–4 and/or PVL, n (%) | 95 (17.8) | 29 (17.7) | 66 (17.9) | 1.000 | 52 (17.4) | 14 (19.7) | 0.730 |
| Surgically-treated NEC, n (%)† | 11 (2.1) | 3 (1.8) | 8 (2.2) | 1.000 | 4 (1.3) | 4 (5.6) | 0.048 |
| Surgically-treated PDA, n (%)† | 31 (5.8) | 5 (3.0) | 26 (7.0) | 0.074 | 13 (4.4) | 13 (18.3) | <0.001 |
| Daily highest glucose concentration, mmol/L, mean (±SD)‡ | 7.9 (2.3) | 5.8 (0.9) | 8.7 (2.2) | <0.001 | 8.2 (1.8) | 10.8 (2.6) | <0.001 |
| Daily lowest glucose concentration, mmol/L, mean (±SD)‡ | 5.6 (1.4) | 4.7 (1.0) | 6.0 (1.4) | <0.001 | 5.9 (1.3) | 6.5 (1.6) | 0.003 |
| Days with hyperglycaemia, mean (±SD)‡ | 3.7 (4.9) | 0 (0) | 5.3 (5.2) | <0.001 | 3.8 (3.5) | 11.3 (6.6) | <0.001 |
| Socioeconomic variables | |||||||
| Education status of the mother, n (%)§ | (n=405) | (n=127) | (n=278) | (n=224) | (n=54) | ||
| ≤9 years | 38 (9.4) | 8 (6.3) | 30 (10.8) | 0.041¶ | 23 (10.3) | 7 (13.0) | 0.588¶ |
| 10–11 years | 26 (6.4) | 12 (9.4) | 14 (5.0) | 13 (5.8) | 1 (1.9) | ||
| 12–13 years | 141 (34.8) | 35 (27.6) | 106 (38.1) | 87 (38.8) | 19 (35.2) | ||
| 14–15 years | 100 (24.7) | 32 (25.2) | 68 (24.5) | 51 (22.8) | 17 (31.5) | ||
| 16 years | 45 (11.1) | 16 (12.6) | 29 (10.4) | 25 (11.2) | 4 (7.4) | ||
| ≥17 years | 55 (13.6) | 24 (18.9) | 31 (11.2) | 25 (11.2) | 6 (11.1) | ||
| Non-Nordic origin of mother, n (%) | 88 (20.2) (n=436) | 16 (11.6) (n=138) | 72 (24.2) (n=298) | 0.002 | 63 (26.1) (n=241) | 9 (15.8) (n=57) | 0.101 |
Hyperglycaemia—glucose concentration measurement >10 mmol/L at least once during the first 28 postnatal days; Student’s t-test and χ2 test were used as appropriate.
*P value for comparison between infants with and without neonatal hyperglycaemia.
†During the first 14 postnatal days.
‡During the first 28 postnatal days.
§Percentage based on known values.
¶P value for overall difference between groups with available data.
CRIB, Clinical Risk Index for Babies; IVH, intraventricular haemorrhage; NEC, necrotising enterocolitis; PDA, patent ductus arteriosus; PVL, periventricular leukomalacia.