Consuming walnuts does not significantly alter blood glucose levels, indicating cardiovascular protective effects of walnuts are not due to improved glycaemic control.
The study involved a systematic review and meta-analysis of previous randomized trials that investigated the effects of walnut consumption on glycaemic control markers such as fasting blood glucose, insulin, and glycated Hb. Studies were found through a comprehensive search of databases including Medline, PubMed, CINAHL, and Cochrane up to March 2nd, 2019. The included studies' risk of bias was assessed using the Cochrane Risk of Bias tool.
In light of the results, although 16 studies were included in the review, it was found that walnut consumption did not significantly impact fasting blood glucose levels or other markers for glycaemic control. Recognizing that the studies included in the analysis were either deemed to have 'some concerns' or 'high risk' of bias, these results suggest that the beneficial effects of walnuts on cardiovascular health aren't caused by improvements in glycaemic control.