Updated September 23, 2015.

We know that carbohydrates affect blood sugar. We also know that the type of carbohydrates we eat, and the amount of carbohydrates we eat at a certain time can also affect blood sugar. But, perhaps there is more to eating than just portions and food choices. Could the order in which we eat affect our blood sugars too?  A study published in the July issue of Diabetes Care suggest that the order in which you eat your meal can have an impact on your after-meal blood sugars.

Eleven subjects with Type 2 diabetes who were treated with metformin (an oral medication) were given a meal containing a fixed amount of calories, fat, protein and carbohydrates. Blood and insulin levels were measured premeal, 30 minutes, 60 minutes and 120 minutes after the meal. The first week participants were instructed to eat (ciabatta bread and orange juice), followed 15 min later by protein (skinless grilled chicken breast) and vegetables (lettuce and tomato salad with low-fat Italian vinaigrette and steamed broccoli with butter). The second week the food order was reversed - vegetables and protein were consumed first, followed by carbohydrates. They found that post-meal glucose levels were 28.6% lower at 30 minutes, 36.7% lower at 60 minutes, and 16.8% lower at 120 minutes when carbohydrates were eaten last. They also found that insulin levels were lower at 60 minutes and 120 minutes too. 

How Can We Interpret These Results? 

There are many things we need to consider when reviewing the results of this study.

Firstly, the type of carbohydrates chosen are simple, refined carbohydrates which can raise blood sugar at a quicker rate and therefore would likely result in a higher blood sugar shortly after a meal. For example, if you have a low blood sugar less than 70mg/dL, you would treat with 15g of simple carbohydrate such as juice and test your blood sugar 15 minutes later. Ingesting juice and white bread and testing blood sugar 30 minutes later would result in a higher blood sugar. I would wonder if changing the composition of carbohydrates, for example by choosing complex carbohydrates, such as whole grains, would change the results of the study.

Secondly, carbohydrate digestion takes about 2 hours to complete. A true post meal blood sugar result is about two hours after a meal. The American Diabetes Association recommends that two hours from the start of a meal, people with diabetes should have a blood sugar of 180mg/dL or less. It would be interesting to see what the actual numbers where two hours after a meal and how different they actually were. If you notice, the reductions in post-meal blood sugars dropped at the two hour mark

Lastly, ingesting protein can help to delay the rise in blood sugars because it takes longer to metabolize. Protein does not contain carbohydrates, however, when eaten in the absence of carbohydrates some protein does turn into carbohydrates. The participates were instructed to eat about 68 g of carbohydrate, which is a higher carbohydrate meal. Would eating a lower carbohydrate meal, rich in protein, make more of an impact than eating protein first? 

Limitations of the Study

Food order and its affect on blood sugar is an interesting and noteworthy topic to explore. This particular pilot study had several limitations. The sample size was small and blood glucose and insulin levels were only measured on two separate occasions. Blood glucose pattern management would need to be more consistent to show a true relationship. We cannot assume a pattern on two measures of blood sugar. Therefore, longer follow up would be important to determine full impact of food order. 

Bottom Line: 

Individuals with diabetes are affected by certain foods differently. It is clear that the amount of carbohydrate and type of carbohydrate you eat can affect your post meal blood sugars. The American Diabetes Association states that carbohydrate amount and available insulin may be the most important factors influencing blood sugar response after eating and should be considered when developing an eating plan. It also suggested to ingest carbohydrates from sources, such as, vegetables, fruits, whole grains, legumes and dairy products over other sources with added sugar, fat and sodium. 

In addition, based on the results of this study, it might be worth testing to see if the order you eat your meal can also make an impact on your blood sugars. Perhaps choosing protein and non starchy vegetables before carbohydrates can reduce your post meal blood sugars. Monitoring your pre and post meal blood sugars can help determine if this method works for you. While the study was flawed, this is a simple change that might be worth trying.

Sources: 

Shukla A, Iliescu R, Thomas C, Aronne L. "Food Order Has a Significant Impact on Postprandial Glucose and Insulin Levels." Diabetes Care. 2015; 38(7):e98-e99. Accessed on-line. September 17, 2015: http://care.diabetesjournals.org/content/38/7/e98.full.pdf+html

American Diabetes Association. Standards of Medical Care in Diabetes – 2015. Diabetes Care. 2015 Jan; 38 (Suppl 1): S1-90.