Nutrient intake order on metabolic outcomes in type 2 diabetes: a systematic review and meta-analysis
Researchers : Luisa M. Saldarriaga-Callejas, Piyush Ratan, Eric Pasqualotto, Ticiane Bovi, Talita Trevisan
Publication year : 2026
Medium : Acta Diabetologica
Tags:
diabetes ,
diet ,
disease ,
endocrinology ,
metabolism ,
therapeutic strategies
Categories:
Clinical ,
Physiology ,
Nutrition
Nutritional management is fundamental to the treatment of type 2 diabetes (T2D), especially for controlling
glycemic variability , which contributes to vascular damage through oxidative stress. This study focuses on evaluating the
"carbohydrate last" (CL) strategy , which involves consuming vegetables, protein, or fat before carbohydrates, as a practical tool for improving metabolic control. The main objective of this meta-analysis was to provide an updated and comprehensive assessment of how this order of intake affects key metabolic parameters in adults with T2D.
Study Methodology
The researchers conducted a systematic search of databases such as PubMed, Embase, and Cochrane up to December 2024.
Seventeen randomized controlled trials (RCTs) with a total of
389 participants were included , most of whom were in the early stages of the disease and were being treated with diet alone or metformin. The criterion for defining the carbohydrate strategy at the end of the trial involved consuming fiber-, protein-, or lipid-rich nutrients up to
30 minutes before carbohydrates .
Results in glucose control
The most significant finding was that
eating carbohydrates last drastically reduces postprandial glucose spikes . Compared to eating carbohydrates first or in a disordered (CF) pattern, the CL group showed:
- A significantly lower glucose level at 60 minutes (average reduction of -42.73 mg/dL).
- A significantly lower glucose level at 120 minutes (average reduction of -13.00 mg/dL).
- Studies using continuous glucose monitoring (CGM) confirmed the consistency of these benefits in reducing glycemic excursions at two hours.
Intestinal hormones and gastric emptying
The strategy of altering the order of foods directly influences digestive physiology:
- A significant increase in postprandial levels of GLP-1 (glucagon-like peptide-1) was observed at 120 minutes.
- Gastric emptying was significantly delayed in the CL group, with a mean difference of 28.14 minutes in mean emptying time.
- No significant differences were found in insulin, glucagon, or GIP levels at 120 minutes, suggesting that the main effect lies in the dynamics of absorption and secretion of incretins.
Proposed physiological mechanisms
The success of this intervention is due to several biological processes: dietary fiber exerts a mechanical effect that delays enzymatic access to carbohydrates, while
proteins and fats stimulate intestinal peptides (such as GLP-1, CCK, and PYY) that inhibit hunger and reduce gastrointestinal transit. Furthermore, the order of macronutrients
improves the alignment between glucose and insulin , smoothing the glycemic curve and reducing the metabolic imbalance typical of type 2 diabetes.
Effects on HbA1c and long-term outcomes
Although the impact on acute levels is clear, the effect on
glycated hemoglobin (HbA1c) was modest but statistically significant (a reduction of -0.16%). This limited reduction is attributed to the fact that most of the analyzed studies had a short follow-up period (less than 3 months), insufficient time to capture larger changes in this marker. However, it is postulated that controlling postprandial peaks could lead to
greater reductions in HbA1c in longer-term interventions .
Clinical feasibility and compliance
One of the greatest advantages of this strategy is its
high acceptability and ease of adoption . Trials evaluating adherence showed that patients follow the meal schedule without reporting adverse effects or distress. It is a
cost-free intervention that does not require calorie restriction or specialized foods, making it sustainable in the long term and adaptable to diverse cultural contexts.
Conclusion
Current evidence supports the use
of the nutrient intake order (carbohydrates last) as a simple and effective strategy to improve the postprandial glycemic profile and enhance GLP-1 secretion in individuals with mild type 2 diabetes. Given its low cost and minimal burden on the patient, this technique represents a practical tool for optimizing diabetes management, although
longer-term studies with populations in advanced stages of the disease are needed to confirm its lasting metabolic benefits and its impact on diabetes-related complications.
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