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Food Order Has Significant Impact on Glucose and Insulin Levels

Eating protein and vegetables before carbohydrates leads to lower post-meal glucose and insulin levels in obese patients with type 2 diabetes, Weill Cornell Medical College researchers found in a new study. This finding, published June 23 in the journal Diabetes Care, might impact the way clinicians advise diabetic patients and other high-risk individuals to eat, focusing not only on how much, but also on when carbohydrates are consumed.

Dr. Louis Aronne's study in Diabetes Care found that insulin and glucose levels were significantly lower when protein and vegetables were eaten before carbohydrates.

"We're always looking for ways to help people with diabetes lower their blood sugar," said senior author Dr. Louis Aronne, the Sanford I. Weill Professor of Metabolic Research and a professor of clinical medicine at Weill Cornell Medical College, who is the study's principal investigator. "We rely on medicine, but diet is an important part of this process, too. Unfortunately, we've found that it's difficult to get people to change their eating habits.

"Carbohydrates raise blood sugar, but if you tell someone not to eat them — or to drastically cut back — it's hard for them to comply," added Dr. Aronne, who is also director of the Comprehensive Weight Control Center at Weill Cornell. "This study points to an easier way that patients might lower their blood sugar and insulin levels."

Patients with type 2 diabetes typically use a finger prick test to check their glucose levels throughout the day. Maintaining normal levels, specifically after meals, is of the utmost importance, because if a diabetics' blood sugar level is consistently high or frequently spikes, they risk complications of their disease, including hardening of the arteries and eventually death from heart disease.

This study looked to validate and advance previous research that showed eating vegetables or protein before carbohydrates leads to lower post-meal glucose levels. This time, though, investigators looked at a whole, typically Western meal, with a good mix of vegetables, protein, carbohydrates and fat.

They worked with 11 patients, all of who had obesity and type 2 diabetes and take an oral drug that helps control glucose levels, called metformin. To see how food order impacted post-meal glucose levels, they had the patients eat a meal, consisting of carbohydrates (ciabatta bread and orange juice), protein, vegetables and fat (chicken breast, lettuce and tomato salad with low-fat dressing and steamed broccoli with butter) twice, on separate days a week apart.

Dr. Louis Aronne
Photo credit: Carlos Rene Perez

On the day of their first meal, researchers collected a fasting glucose level in the morning, 12 hours after the patients last ate. They were then instructed to eat their carbohydrates first, followed 15 minutes later by the protein, vegetables and fat. After they finished eating, researchers checked their post-meal glucose levels via blood test at 30, 60 and 120-minute intervals. A week later, researchers again checked patients' fasting glucose levels, and then had them eat the same meal, but with the food order reversed: protein, vegetables and fat first, followed 15 minutes later by the carbohydrates. The same post-meal glucose levels were then collected.

The results showed that glucose levels were much lower at the 30, 60 and 120 minute checks — by about 29 percent, 37 percent and 17 percent, respectively — when vegetables and protein were eaten before the carbohydrates. Insulin was also significantly lower when protein and vegetables were eaten first. This finding confirms that the order in which we eat food matters, and points to a new way to effectively control post-meal glucose levels in diabetic patients.

"Based on this finding, instead of saying ‘don't eat that' to their patients, clinicians might instead say, ‘eat this before that,'" Dr. Aronne said. "While we need to do some follow-up work, based on this finding, patients with type 2 might be able to make a simple change to lower their blood sugar throughout the day, decrease how much insulin they need to take, and potentially have a long-lasting, positive impact on their health."

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