The participants either ate vegetables, protein, and fat up to 30 minutes before carbohydrates (carbohydrate last) or ate carbohydrates first (or simultaneously) with other foods (carbohydrate first). Most of the participants had mild, early-stage type 2 diabetes managed with diet or metformin alone.

Compared to the carbohydrate-first pattern, the carbohydrate-last pattern reduced postprandial blood glucose by 43 mg/dL at 60 minutes and by 13 mg/dL at 120 minutes. It also increased GLP-1 secretion and delayed gastric emptying.

In 4 long-term studies, using a carbohydrate-last pattern for 10 weeks to 24 months reduced HbA1c to a small degree (−0.16%).

The evidence quality was judged as moderate to high.

Last but not least: Can changing the order you eat foods help manage diabetes? Original paper