A randomized placebo-controlled trial of the effect of coffee consumption on insulin sensitivity: Design and baseline characteristics of the Coffee for METabolic Health (COMETH) study

Abstract

BackgroundCoffee consumption has been consistently associated with a lower risk of type 2 diabetes mellitus in cohort studies. In addition, coffee components increased insulin sensitivity in animal models. However, data from intervention studies on the effect of coffee consumption on glucose metabolism have been limited by small sample sizes, lack of blinding, short follow-up duration and the use of surrogate indices of insulin sensitivity. We designed the Coffee for Metabolic Health (COMETH) study to evaluate the effect of coffee consumption on insulin sensitivity.MethodologyThe COMETH study is a double-blind randomized placebo-controlled 24-week trial. Participants were overweight, male and female habitual coffee consumers who were of Chinese, Malay and Asian-Indian ethnicity. We excluded smokers, persons with diabetes, and persons with low insulin resistance (HOMA-IR < 1.30). Participants were randomly assigned to receive daily 4 cups of instant regular coffee or 4 cups of a coffee-like placebo beverage. The hyperinsulinemic euglycemic clamp was performed at baseline and at the end of 24 weeks to determine changes in the bodyweight standardized M-value. Secondary outcomes included changes in fasting glucose and insulin sensitivity mediators such as adiponectin, markers of inflammation, liver function, and oxidative stress.We enrolled 128 participants, 126 (57.1% males; aged 35–67 years) of whom completed baseline assessments.DiscussionIf improvement in insulin sensitivity in the coffee group is significantly greater than that of the placebo group, this would support the hypothesis that coffee consumption reduced risk of type 2 diabetes through biological pathways involving insulin sensitivity.Trial registrationClinicalTrials.gov identifier: NCT01738399. Registered on 28 November 2012. Trial Sponsor: Nestlé Research Center, Lausanne, Switzerland. Trial Site: National University of Singapore.

Coffee Consumption and the Risk of Metabolic Syndrome in the ‘Seguimiento Universidad de Navarra’ Project

“…Coffee consumption and coffee micronutrient components have been suggested to improve glucose metabolism, lower inflammation, and decrease liver damage in animal models [ 12 , 13 ]. Further evidence suggests that it improves endothelial function, aids in loss of fat mass and is associated with favorable plasma biomarkers of metabolic and inflammatory pathways [ 14 , 15 , 16 ]. A recent metanalysis of randomized controlled trials by Ramli et al investigated the effects of coffee consumption on anthropometric measurements, glycemic indices, lipid profiles, and blood pressure and found all of these parameters were improved by green coffee extract supplementation [ 17 ].…”

Association of coffee consumption with type 2 diabetes and glycemic traits: a Mendelian randomization study

“…Type 2 diabetes (T2D) is a leading cause of mortality and morbidity worldwide [ 1 2 3 4 ], with an estimated prevalence of 9.3% [ 1 ], 67.9 million disability-adjusted life-years [ 2 ] and increase in treatment cost [ 3 ] worldwide. Evidence for the physiological significance of habitual coffee consumption on T2D manifestations keeps evolving, with some cohort studies [ 5 6 7 8 ] and randomized trials [ 9 10 ] suggesting an inverse association, but others [ 11 12 ] found a null association. The limitations of these trials included small sample sizes and a short follow-up period.…”

The Coffee Diterpene, Kahweol, Ameliorates Pancreatic β-Cell Function in Streptozotocin (STZ)-Treated Rat INS-1 Cells through NF-kB and p-AKT/Bcl-2 Pathways

“…Coffee is among the most extensively consumed drinks globally; it contains many effective anti-diabetic compounds, including caffeine, kahweol, cafestol, and chlorogenic acid [ 12 , 13 , 14 , 15 , 16 , 17 , 18 ]. On the other hand, literature reported that high coffee consumption is associated with some adverse effects such as gastrointestinal disturbances, tachycardia, and sleep disorders.…”