Controlling postprandial glucose variability remains a challenge for people living with type 1 diabetes. In addition to carbohydrate, recent systematic reviews have identified fat and protein as modifiers of the postprandial glycaemic profile. 1,2 Dietary fat and protein have been shown to significantly increase and delay the peak glucose excursion 3,4 and

Aim: To determine the insulin requirement for a high-fat, high-protein breakfast to optimise postprandial glycaemic excursions in children and young people with type 1 diabetes using insulin pumps. Methods: In all, 27 participants aged 10-23 years, BMI <95 th percentile (2-18 years) or BMI <30 kg/m 2 (19-25 years) and HbA 1c ≤64 mmol/mol (≤8.0%) consumed a high-fat, high-protein breakfast (carbohydrate: 30 g, fat: 40 g and protein: 50 g) for 4 days. In this cross-over trial, insulin was administered, based on the insulin-to-carbohydrate ratio (ICR) of 100% (control), 120%, 140% and 160%, in an order defined by a randomisation sequence and delivered in a combination bolus, 60% ¼ hr premeal and 40% over 3 hr. Postprandial sensor glucose was assessed for 6 hr. Results: Comparing 100% ICR, 140% ICR and 160% ICR resulted in significantly lower 6-hr areas under the glucose curves: mean (95%CI) (822 mmol/L.min [605,1039] and 567 [350,784] vs 1249 [1042,1457], p ≤ 0.001) and peak glucose excursions (4.0 mmol/L [3.0,4.9] and 2.7 [1.7,3.6] vs 6.0 [5.0,6.9],p < 0.001). Rates of hypoglycaemia for 100%-160% ICR were 7.7%, 7.7%, 12% and 19% respectively (p ≥ 0.139). With increasing insulin dose, a step-wise reduction in mean glucose excursion was observed from 1 to 6 hr (p = 0.008). Conclusions: Incrementally increasing the insulin dose for a high-fat, high-protein breakfast resulted in a predictable, dose-dependent reduction in postprandial glycaemia: 140% ICR improved postprandial glycaemic excursions without a statistically significant increase in hypoglycaemia. These findings support a safe, practical method for insulin adjustment for high-fat, high-protein meals that can be readily implemented in practice to improve postprandial glycaemia. K E Y W O R D Schildren and adolescents, endocrinology, insulin therapy, nutrition and diet, self-management 2 of 8 | SMITH eT al.

Globally, continuous glucose monitoring is changing the landscape of type 1 diabetes clinical management. The increasing, widespread use of this technology has been accompanied by an unprecedented level of interest in the dynamics of the postprandial glycaemic profile and in turn, a demand for clinical explanations for aberrant postprandial glycaemic patterns. 1 To manage postprandial glycaemia in practice, insulin is administered prior to meal consumption at a dose that is adjusted to the carbohydrate content of the meal. 2 Often, despite accurate carbohydrate counting and insulin dose calculation, there is dysglycaemia. 3 Research has identified a significant contribution of other dietary factors, including fat and protein to this postprandial glycaemic variability. 4,5 It has been demonstrated that fat and/ or protein when consumed in