Differentiating Transient Idiopathic Hyperglycaemia and Neonatal Diabetes Mellitus in Preterm Infants

Transient idiopathic hyperglycaemia (TIH) is partly due to defective processing of proinsulin to insulin in preterm neonates, whereas transient neonatal diabetes mellitus (TNDM) is a rare genetic form of pancreatic β-cell dysfunction. Distinguishing these two conditions is difficult yet essential to allow personalised management and genetic testing. Here we investigated whether metabolic or therapeutic features contributed to the diagnosis in preterm neonates.

We prospectively included 13 preterm neonates with TIH between 2008 and 2011, and we identified 2 patients with TNDM in the French neonatal diabetes cohort registry. All of them were born before 32 weeks of gestation. We compared clinical features, glycaemic profiles, insulin dosages, and nutritional intakes.

TNDM patients had higher day-1 glycaemia levels before insulin therapy [median 23.5 (20-27) vs. 13.6 (10.7-19.8) mmol/l, p = 0.025] and higher insulin requirements [median 1.2 (0.9-1.5) vs. 0.8 (0.3-0.9) IU/kg/day, p = 0.037] compared to TIH. They also required insulin therapy earlier [median 0.75 (0.5-1) vs. 2 (0.5-7) days, p = 0.036] and for a longer time [median 85 (57-113) vs. 11 (4-15) days, p = 0.036].

TNDM and TIH are different clinical and genetic entities with specific pathophysiological mechanisms. Metabolic and therapeutic features may help to detect TNDM in preterm neonates as soon as day-1 of hyperglycaemia.