Coffee Consumption and Type 2 Diabetes Study

Patients with type 2 diabetes are at a risk for developing complications of micro-and macrovascular diseases. Coffee is one of the most popular beverages around the world, known to have active biocompounds like caffeine, chlorogenic acids, and diterpenes that have antioxidant, anti-inflammatory, and anti-mutagenic properties in humans.

A new study by Hossein Shahinfar and their team discusses the risks of coffee consumption in type 2 diabetic patients relating to cardiovascular diseases. The study is published in Nutrition, Metabolism & Cardiovascular Diseases.

Study Objective

The objective of the study was to evaluate the long-term consequences of coffee drinking in patients with type 2 diabetes. Coffee consumption and the risk of mortality from all causes, CVD, and CHD needed to be evaluated.

Methodology

The researchers used PubMed, Scopus, and Web of Sciences as search portals until November 2020 for prospective cohort studies evaluating the association of coffee drinking with the risk of cardiovascular disease (CVD) and mortality in patients with type 2 diabetes. Two reviewers extracted data and rated the certainty of evidence using the GRADE approach. Random-effects models were used to estimate the hazard ratios (HRs) and 95% CIs. Dose-response associations were modeled by a one-stage mixed-effects meta-analysis.

Results

The researchers included ten prospective cohort studies with 82,270 cases. They found that compared to those with no coffee consumption, the HRs for consumption of 4 cups/day were:

• 0.79 (95%CI: 0.72, 0.87; n = 10 studies) for all-cause mortality
• 0.60 (95%CI: 0.46, 0.79; n = 4) for CVD mortality
• 0.68 (95%CI: 0.51, 0.91; n = 3) for coronary heart disease (CHD) mortality
• 0.72 (95%CI: 0.54, 0.98; n = 2) for CHD
• 0.77 (95%CI: 0.61, 0.98; n = 2) for total CVD events

There was no significant association for cancer mortality and stroke. There was an inverse monotonic association between coffee drinking and all-cause and CVD mortality, and an inverse linear association for CHD and total CVD events. The certainty of evidence was graded moderate for all-cause mortality, and low or very low for other outcomes.

Conclusion

The researchers concluded that "Drinking coffee may be inversely associated with the risk of mortality in patients with type 2 diabetes. However, more research is needed considering the type of coffee, sugar and cream added to coffee, and history of CVD to present more confident results." They also stated that more prospective studies considering diabetes duration, degree of glycemic control, and medications used could help present more confident conclusions for the long-term consequences of coffee drinking in patients with type 2 diabetes.

Further Information

Hossein Shahinfar, Ahmad Jayedi, Tauseef A. Khan, Sakineh Shab-Bidar "Coffee consumption and cardiovascular diseases and mortality in patients with type 2 diabetes: A systematic review and dose-response meta-analysis of cohort studies" Nutrition, Metabolism & Cardiovascular Diseases (2021) 31, 2526-2538.