Background/Objectives: Milk contributes with saturated fat, but randomized controlled studies (RCT) on the effects of dairy on risk of type-2 diabetes (T2D) where dairy is given as whole foods are scarce. The objective of our study was to investigate the long-term effects of semi-skimmed milk on insulin sensitivity and further to compare milk with sugar-sweetened soft drinks (SSSD).
Subject/Methods: A secondary analysis of a 6-mo RCT with 60 overweight and obese subjects randomly assigned to 1 L/d of either milk (1.5 g fat/100 ml), SSSD, non-calorie soft drink (NCSD) or water was conducted. Insulin sensitivity was evaluated by oral-glucose tolerance test (OGTT) and plasma free fatty acids. Secondarily, fasting blood lipids, blood pressure and concentration of plasminogen activator inhibitor-1 were assessed.
Results: There were no differences between milk, SSSD, NCSD and water on insulin sensitivity assessed by OGTT (Matsuda-index, fasting and area under the curve glucose, insulin and homeostasis model assessment values). SSSD increased total cholesterol compared to NCSD (P =0.007), and triacylglycerol compared to NCSD and water (P = 0.045 and P = 0.045, respectively). No other parameter differed significantly between the groups.
Conclusions: There were no differences in effect between intake of milk, SSSD, NCSD and water (1 L/d) for 6-mo on risk-markers of T2D in overweight and obese adults. Moreover the results indicate that milk is neutral in its effect on risk of T2D and CVD and that SSSD affects risk markers of CVD but not of T2D compared to the other beverages.
The key finding of this 6-month randomised controlled trial is that a long-term daily consumption of 1L of milk, sugar-sweetened beverage (SSB), low calorie sweetened drink and water had no effects on insulin sensitivity and on risk markers of type 2 diabetes in 60 overweight or obese adults.
Furthermore, the daily consumption of the low calorie sweetened drink (1L/day) for 6 months had favourable effects on total cholesterol and triglycerides blood levels compared to the sugar-sweetened version.
Overall, this new study adds further evidence to previous findings showing that the consumption of low calorie sweeteners in drinks do not affect insulin resistance or other diabetes markers, while on the contrary, they may have a favourable effect in other cardiometabolic factors. Read our interview with the authors here.