OBJECTIVES: To study the effect of postmeal Fast-acting insulin Aspart (Fiasp METHODS: A single-center trial was conducted among 65 pre-school children (6 mo to 6 y) with Type 1 diabetes for at least 6 mo, on multiple daily insulin injections. Children were randomized to receive their meal bolus postmeal or premeal for the first 3 mo, followed by cross-over at 3 mo. The two groups were compared at the end of 6 mo for the change in frequency of hypoglycemia and hyperglycemia, HbA1c, glycemic variability, and parental satisfaction. Ten children (5 in each group) underwent pharmacokinetic studies. The trial was approved by Institutional Ethics Committee and registered with the Controlled Trial Registry of India vide no CTRI/2020/10/028750. RESULTS: Fifty-four children completed the study, with 27 children in each group. There were no significant differences in the frequency of clinical (p = 0.921), severe (p = 0.167) or serious (p = 0.753) hypoglycemia in the two groups. There were no differences in secondary outcome parameters and pharmacokinetics. CONCLUSIONS: The premeal or postmeal injection of Fiasp TRIAL REGISTRATION: The trial is registered with the Controlled Trial Registry of India vide no CTRI/2020/10/028750.