An meta-analysis of studies presented at this year's Annual Meeting of the European Association for the Study of Diabetes in Barcelona, Spain (16-20 September) shows that recommendations to moderate alcohol consumption for people with type 2 diabetes (T2D) may need to be reviewed, since low-to-moderate consumption could have a positive effect on blood glucose and fat metabolism.

The study is by Yuling Chen, Southeast University, Nanjing, China, and Dr Li Ling, Director of the Department of Endocrinology, Zhongda Hospital and School of Medicine, Southeast University, Nanjing, China and colleagues.

However, regardless of the effects on metabolism shown by this analysis, advice from various diabetes organisations including Diabetes UK remains that people with T1D or T2D need to be careful with alcohol consumption, since drinking can make you more likely to have a hypoglyaemic episode (known as a hypo) because alcohol makes your blood sugars drop. It can also cause weight gain and other health issues.

The authors studied PubMed, Embase, and Cochrane databases up to March 2019 for randomised controlled trials (RCTs) that assessed the relationship between alcohol consumption and glucose and lipid metabolism among adults with T2D. Extracted data from RCTs were analysed using computer modelling.

The authors found ten relevant RCTs involving 575 participants that were included in this review. Meta-analysis showed that alcohol consumption was associated with reduced triglyceride levels and insulin levels, but had no statistically significant effect on fasting blood glucose levels, glycated haemoglobin (HbA1c, a measure of blood glucose control), or total cholesterol, low density lipoprotein (bad) cholesterol, and high density lipoprotein (good) cholesterol.

Subgroup analysis indicated that drinking light to moderate amounts of alcohol decreased the levels of triglycerides (blood fats) and insulin in people with T2DM. Light to moderate drinking was defined by the authors as 20g or less of alcohol per day. This translates to approximately 1.5 cans of beer (330ml, 5% alcohol), a large (200ml) glass of wine (12% alcohol) or a 50ml serving of 40% alcohol spirit (for example vodka/gin).

The authors conclude: "Findings of this meta-analysis show a positive effect of alcohol on glucose and fat metabolism in people with type 2 diabetes. Larger studies are needed to further evaluate the effects of alcohol consumption on blood sugar management, especially in patients with type 2 diabetes."