Effect of a low dose whey/guar preload on glycemic control in people with type 2 diabetes-a randomized controlled trial

Objective: Large preloads of protein and fat have been shown to lower glucose after a carbohydrate-rich meal in people with type 2 diabetes but add a considerable energy burden. Low calorie preloads [<5% of daily energy intake] have been tested in this study in people with prediabetes and with type 2 diabetes.

Research design and methods: This was an unblinded randomized crossover study with two placebo days and two active treatment days. Glucose was measured for 3 hours with fingerprick samples as well as continuous glucose monitoring [CGMS]. Twenty-four subjects with pre-diabetes or moderately controlled type 2 diabetes [fasting glucose < 10 and HbA1c < 8.5%] were recruited. The preload contained 17 g whey protein plus 3 g lactose and 5 g guar, and 1 g flavor material [including sucralose] dissolved in 150 ml cold water or 150 ml cold water with no additives. The breakfast test meal consisted of 2 slices of bread, margarine and jam [3 slices for men] with the test drink 15 minutes beforehand.

Results: Peak fingerprick glucose was reduced by 2.1 mmol/L at 45 min [p < 0.0001]. Average fingerprick glucose over 3 hours was reduced by 0.8 mmol/L [p = 0.0003]. There was no difference between those with diabetes or prediabetes or those on medication or not on medication.

Conclusions: An 80 kcal whey protein/fiber preload can lower average glucose over 3 hours by 0.8 mmol/L. If used long term before at least two carbohydrate-rich meals/day this preload could lower HbA1c by up to 1%.

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Alex’s Notes: I’m sure you can already guess the outcome of this study based on the title. We know that dairy in general has numerous beneficial effects on metabolic syndrome, and more specifically, whey protein has been shown to be more effective than soy protein at reducing appetite and caloric intake while preserving lean body mass. Moreover, a 55g whey protein preload drink has demonstrated the ability to reduce gastric emptying, increase glucagon-like peptide 1 and insulin, and overall lower post-meal glucose levels by 54 mg/dL.

There is whey more evidence to support the beneficial effects of whey in type-2 diabetics, but how about the other nutrients? I’m talking fiber people. Fat also holds some benefit, but that comes at the expense of considerable amount of calories and little benefit outside the glycemic control. The current study wanted to keep things low-calorie so as to help during weight loss interventions should the results pan out. Thus, they replaced a considerable amount of the 55g whey bolus previously demonstrated to be successful with some guar gum fiber.

Twenty-four subjects (13 with type-2 diabetes & 11 with prediabetes) were recruited to participate. The only exclusion criteria were attempts at weight loss or use of insulin and/or any medications other than metformin. The preload was 17g of whey protein plus 3g of lactose and 5g of guar gum with 1g of flavoring (including either stevia or sucralose) dissolved in 150mL of cold water. The control condition was just the cold water.

What did the researchers do?

The study lasted five days. The first was to get everything set up, and the next four days were interventions. The subjects were hooked up with a continuous glucose monitoring system (CGMS) that recorded blood glucose values every five minutes for all five days. Additionally, finger pricks for blood glucose were conducted four times per day for comparison to the CGMS, and were also taken before the test meal and then every 15 min for the first hour, then at 90 min, 120 min and 180 min.

The test meal was two slices of bread (three for men) with margarine (really????) and jam plus tea/coffee if desired, which was standardized to be consistent across all four test days. The preload of whey/fiber or water control was consumed 15 minutes before the test meal, and all subjects consumed the whey/fiber on two of the days and the water on two of the days in a randomized order. Also, the test meal was consumed in the morning with all medications taken as least 15 minutes before the test drink, and a packaged pre-test meal was provided the night before each test to standardize conditions.

What was found?

The average age of the subjects was 60 years and the average BMI was 32, and nine of the subjects were on metformin. The CGMS revealed that the average effect of the drink was a significant peak reduction of 19 mg/dL, with the effect ranging from an increase of 23mg/dL to a reduction of 42mg/dL. There were no effects beyond 3 hours after the test meal, no difference in response between the people with diabetes and prediabetes, and there was no relationship between fasting glucose response and the effect of the drink.

The finger prick data supported the above and showed that the whey/fiber drink significantly reduced blood glucose by 20mg/dL at 15 minutes, 23mg/dL at 30 minutes, 38mg/dL at 45 minutes, 30mg/dL at 60 minutes, and 18mg/dL at 90 minutes. Overall, peak glucose was reduced by 25mg/dL and it took an additional 30 minutes for this peak to be reached. Average glucose over the 3 hours post-meal was reduced by 14mg/dL.

The takeaway

Whey and fiber for the win when your goal is acute glucose management. How would this translate into long term changes in HbA1c and co? This study can’t tell us that. It is also unfortunate that they did not include whey only and fiber only groups for comparison. Some data on the insulin response would have been nice too. Regardless, whey and fiber is a cheap and effective method for acute glycemic control, and can easily be taken before multiple meals of the day. Don’t like drinks? Then eat a Questbar.


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