Effect of different protein diets on glucose and insulin metabolism and substrate partitioning

A high protein diet in type 2 diabetics for 5 weeks showed an improvement of
the 24 h glycemic profile and lower Triglyceride (TG) and Free Fatty Acids
(FFA) [9]. It suggests that the low GI property of (dairy) protein gives
glycemic improvements leading to a better body weight control despite the
strong insulinotropic properties, which are comparable to high GI food. This
hints to an improvement of the insulin sensitivity due to the stimulatory
insulin secretion effect using high (diary) protein diets. Therefore, it is
important to get a better insight in the role of dietary (dairy) proteins on
glycemic profile and in particular its role on insulin metabolism and substrate
partitioning. Also the role of diary proteins compare to other protein sources
in relation to the post-prandial response on metabolic markers is not known.
For that reason, experimental studies with different (dairy) protein and GI
diets will be investigated in this study.

The presently proposed study aims to investigate how dairy proteins compare to
vegetable protein and carbohydrate sources leads to glucose and insulin
metabolism and substrate partitioning.

Subjects are exposed to four different diets. To have a same baseline condition
before each diet, subjects have to standardize the 3 days before the tests.
Therefore food-intake and activity diaries have to be filled out before the
first test day and repeated before the other test days.
Each respiration chamber visit starts after the continuous glucose monitoring
system (CGMS) placement plus preparation time at 21.00h and ends 36 hours later
at 9.00h. The first twelve hours are to accustom to the respiration chamber.
Then, energy expenditure measurements are made during 24 hours at a temperature
of 22°C. During the respiration chamber visit, hourly (during daytime)
sleepiness-questionnaires and daily sleep-questionnaires will be filled out.
Also VAS satiety scale questionnaire has to be filled out before and hourly
after a meal. Also bloodsamples will be taken at 0, 30, 60, 120 and 240 minutes
postprandially after the three meals.

1. 15% dairy protein and low GI
2. 25% dairy protein and low GI
3. 15% vegetable protein and low GI
4. 15% dairy protein and high GI (specific details of the diet in appendix)

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