This review provides the epidemiologic and research evidences documenting the effects of coffee consumption on type 2 diabetes mellitus (T2DM). We summarize the literature concerning the effects of coffee consumption on different mechanistic factors involving in pathogenesis of T2DM, such as glucose tolerance, insulin sensitivity, insulin resistance, glucose-6-phosphatase, intestinal glucose absorption, antioxidant activity, inflammatory biomarkers, nuclear factor-κB inhibition, glucose uptake, glucose homeostasis, glucose metabolism, and insulin secretion. These factors play a crucial role in influencing the normal levels of glucose in blood. Overall, the experimental and epidemiologic evidences presented here elucidate the protective effects of coffee consumption on T2DM, involving multiple preventive mechanisms. Despite the firm evidences available through a growing literature base, it is still uncertain whether the use of coffee should be recommended to patients with diabetes and/or any patient who might be at the risk of T2DM as a supplementary therapy to prevent further progression of T2DM.
Alex’s Notes: More love for everyone’s favorite drink. This review is short and sweet with a focus on something that plagues nearly 10% of the population – diabetes. Its purpose is to explore and summarize the current science on the potential effects of coffee consumption. What is coffee? Seriously, until reading this review I never really knew. I mean, we all know what coffee is, but do you actually know what coffee is?
“Coffee is a mixture of many chemicals such as carbohydrates, lipids, vitamins, nitrogenous compounds, isoflavonoids, and micronutrients. The major components of coffee are caffeine, cafestol and kahweol, chlorogenic acid (CGA), and micronutrients.”
Coffee has many well-known benefits with regard to athletic performance and cognition, but unfortunately these effects are only in non-habitual drinkers and likely due to the caffeine. But assuming you ignore this, maybe we can still get a good placebo effect. No matter how often you consume it, having a nice cup of Joe in the morning always seems to be a good start to the day. No doubt the caffeine in coffee plays an important role in its benefits, but not all effects stem from it. Numerous epidemiologic studies have associated coffee consumption with a reduced risk of diabetes, and one study found the protective effects to be stronger with decaffeinated coffee.
This is where the other components come into play. Notably, all the aforementioned compounds are antioxidants that not only reduce inflammatory markers but also increase anti-inflammatory markers. Given the role of chronic low-grade inflammation in diabetes, this can be nothing but beneficial. Moreover, CGA specifically has been shown to stop the activation of various pro-inflammatory biomarkers via inhibition of nuclear factor (NF)-kB, as well as suppress glucose-6-phosphatase and subsequently reduce hepatic glucose production. Importantly, these effects were observed in cell cultures or rats, but we need some form of explanation for the coffee benefits, and until proven otherwise these effects in humans are plausible. On a final note, it has been shown that coffee is able to boost the antioxidant profile of humans with consumption.
Interestingly, diabetes is associated with low magnesium levels, and the authors of the review at hand speculate that coffee may benefit diabetics through its magnesium content as well. It is possible, but from a practical standpoint, not likely, as coffee only contains 7mg of magnesium per cup. But who cares, coffee is awesome.