- Giving mice olive oil before glucose reduced the early rise in blood sugar compared with giving the oil afterwards.
- The effect involved slower stomach emptying and signalling through glucagon, GLP-1 and nerve pathways.
- This was animal research and does not prove that drinking olive oil before meals improves diabetes control in humans.
The order in which foods are eaten may influence how quickly blood glucose rises after a meal, according to new research from Kyoto University.
Scientists investigating the relationship between carbohydrates and blood glucose found that giving mice olive oil before glucose reduced the initial rise in blood sugar.
The study, published in the journal Diabetes on 8 October, examined how hormones and nerves contribute to this response.
Researchers were particularly interested in gastric emptying – the process by which food moves from the stomach into the small intestine.
This process can strongly influence post-meal blood glucose levels.
What did researchers discover?
Mice received olive oil before an oral glucose dose, after glucose, or water as a comparison.
When olive oil was given before glucose, the initial rise in blood sugar was smaller.
Researchers also observed slower gastric emptying.
At the same time, several hormones increased, including GLP-1, GIP and glucagon.
GLP-1 is particularly relevant to type 2 diabetes because it helps regulate glucose levels after eating.
The results were also observed in mouse models of diabetes and severe insulin deficiency.
Why was glucagon involved?
Glucagon is usually associated with increasing blood glucose by stimulating the liver to release stored glucose.
However, the researchers found that its role in this response was more complicated.
Blocking glucagon signalling alone did not eliminate the effect.
Neither did blocking GLP-1 signalling alone.
When both pathways were blocked together, the glucose-lowering response weakened and the effect on gastric emptying disappeared.
Further experiments suggested that signalling through the vagus nerve also contributed.
This indicates that meal sequencing may engage several overlapping mechanisms rather than simply changing how quickly nutrients are absorbed.
Does eating fat before carbohydrates improve glucose control?
There is some existing human research suggesting that consuming vegetables, protein or fat before carbohydrates can influence post-meal glucose responses.
However, the current study was specifically designed to investigate the biological mechanisms in mice.
It does not establish the ideal order in which people with diabetes should eat their meals.
It also does not show that consuming additional olive oil will improve HbA1c or reduce diabetes complications.
Olive oil contains substantial energy, so adding large quantities to the diet could increase calorie intake.
What does this mean for the UK?
For people managing diabetes through dietary changes, the findings provide another reason for researchers to investigate meal composition and food order.
However, the overall balance of a meal remains important.
That includes the type and amount of carbohydrate, the quality of dietary fats and the inclusion of fibre-rich foods.
Olive oil can form part of a Mediterranean-style diet, but this particular experiment does not justify drinking it before meals as a diabetes treatment.
People using insulin or other glucose-lowering medicines should not change their doses based on these findings.
The study provides a possible explanation for why the order of nutrients can affect glucose responses.
Whether deliberately changing meal order produces meaningful long-term benefits in people with diabetes remains a question for human trials.
Primary study: Olive Oil Before Oral Glucose Delays Gastric Emptying and Lowers Glycemia Through Partially Redundant Glucagon and GLP-1 Signaling in Mice – Diabetes