The effect of a low glycaemic index diet on reducing day-long glycaemia in healthy young adults: a randomized crossover trial

Abstract

Aim: To compare the effect of a low glycaemic index (LGI) diet on reducing day‐long glycaemia with a macronutrient‐matched high glycaemic index (HGI) diet, using customized meal delivery to ensure compliance. Materials and Methods: We conducted a single‐blinded, randomized crossover trial in 14 healthy adults (57% female) with a mean ± SD age of 21.6 ± 1.7 years. A flash glucose monitoring sensor was installed on the subjects on day 1 to capture the interstitial glucose level every 15 minutes for 14 days. Subjects were randomized to receive an LGI (dietary GI = 40) or HGI (dietary GI = 60) diet (three meals and two snacks) from day 2 for 5 consecutive days, followed by a 2‐day washout, then switched to the alternative diet for another 5 days. A paired t‐test was used to test the differences in the incremental area under the curve (iAUC) of glucose, postprandial glucose (PPG) concentration and maximum postprandial glucose rise (MPGR) between the LGI and HGI periods. Results: Subjects had lower iAUC for average day‐long glycaemia during the LGI intervention period compared with the HGI period (mean ± SD, 865 ± 297 vs. 1024 ± 267 mmol x min/L; P = .047). PPG for breakfast and snack 2, and MPGR for breakfast, snack 2 and dinner, were lower in the LGI period. Conclusions: In young healthy adults, following an LGI diet resulted in lower average day‐long glycaemia compared with a macronutrient‐matched HGI diet. Our results support the use of LGI diets to reduce the risk of developing glucose intolerance.