A randomized crossover study to assess the effect of an oat-rich diet on glycaemic control, plasma lipids and postprandial glycaemia, inflammation and oxidative stress in Type 2 diabetes

Abstract

Aims: In the UK, lifestyle intervention is first-line management in Type 2 diabetes. It is unclear what type of diet is most efficacious for improving glycaemic control. This study investigated the effects of an oat-enriched diet on glycaemic control, postprandial glycaemia, inflammation and oxidative stress compared with standard dietary advice.

Methods: In a randomized crossover design, 27 volunteers with Type 2 diabetes, managed on diet and lifestyle only, were observed for two consecutive 8-week periods following either the oat-enriched diet or re-enforced standard dietary advice. Volunteers attended at baseline (habitual intake) and 8 and 16 weeks. Measurements included basic clinical measurements and fasted and postprandial (3-h) glucose and insulin in response to a healthy test meal. Markers of inflammation and oxidative stress, including high-sensitivity C-reactive protein, interleukin 6, interleukin 18, tumour necrosis factor-alpha, adiponectin, thiobarbituric acid reactive substances, oxygen radical antioxidant capacity, oxidized LDL and urinary isoprostanes, were also measured at fasting and in the postprandial period.

Results: There were no diet-related effects on glycaemic control or glycaemic or insulinaemic responses to the test meal. Total cholesterol (5.1 ± 1.0 vs. 4.9 ± 0.8 mmol/l, P = 0.019) concentrations declined following the oat-enriched diet compared with standard dietary advice. There was a postprandial decline in adiponectin concentration (P = 0.009), but no effect of dietary intervention. None of the measures of oxidative stress or inflammation were altered by the oat-enriched diet compared with standard dietary advice.

Conclusion: The oat-enriched diet had a modest impact on lipid lowering, but did not impact on oxidative stress or inflammation in these volunteers with Type 2 diabetes.

Figure 1

Glycaemic response to standard test meal at baseline and following dietary intervention. Values are means. Habitual (pre-intervention) (); standard dietary advice (); oat-enriched diet (). Effect of time, P < 0.001. Effect of diet, P = 0.036. Interaction between postprandial time × diet, P < 0.001.

Figure 2

Insulinaemic response to standard test meal at baseline and following dietary intervention. Values are means. Habitual (pre-intervention) (); standard dietary advice (); oat-enriched diet (). Effect of postprandial time, P < 0.001. Effect of diet, P = 0.967. Interaction between postprandial time × diet, P = 0.774.

Figure 3

Adiponectin concentrations following the standard test meal at baseline and following dietary intervention. Values are means. Habitual (pre-intervention) (); standard dietary advice (); oat-enriched diet (). Effect of time, P = 0.009. Effect of diet, P = 0.452. Interaction between postprandial time × diet, P = 0.582.