Aim To assess interpersonal postprandial glucose responses (PPGRs) to meals matched for energy, macronutrient content, glycaemic index (GI) and insulin administration in people with type 1 diabetes.

Methods One hundred and twenty people with type 1 diabetes (mean ± SD: Age 31 ± 7 years, BMI 26.9 ± 2.3kg.m2, HbA1c 7.6 ± 0.8% [55.8 ± 8.2mmol/mol]) consumed two carbohydrate-based standardised meals (millet oat-porridge [OP] or shredded wheat [SW]), twice, on four separate occasions. Each meal was matched for energy, fibre, and macronutrient composition (carbohydrate=1g/kg), GI, and prandial insulin administration. Continuous glucose monitoring captured interstitial glucose (IG) responses for 240min following the consumption of each meal.

Results Despite identical energy, fibre and macronutrient content, GI and prandial insulin administration, the average PPGR differed significantly between OP and SW respectively (IG AUC: 1807 ± 588 vs 1678 ± 533mmol/l/min; p=0.05). PPGRs to each meal type showed a high degree of reproducibility within individuals (OP r=0.994, p < 0.001 vs SW r=0.987 p < 0.001), but large interpersonal variation within each meal type (CV%: OP 32.5% vs SW 31.7%). Higher PPGR was positively associated with PPGR variability (r=0.698, p < 0.001), HbA1c (r=0.223, p=0.014), BMI (r=0.316, p < 0.001), and Age (r=0.277, p < 0.001).

Conclusions People with type 1 diabetes exhibit significant interpersonal PPGRs independent of energy, fibre and carbohydrate content, GI and prandial insulin administration. This highlights that variability in mealtime glucose control is interpersonal, and influenced by personal characteristics and/or food features beyond those currently used to inform mealtime self-management recommendations.