February 14, 2009

Coffee, Caffeine, and Risk of Type 2 Diabetes

In many studies, high consumption of coffee has been shown to lower ones risk of developing type 2 diabetes. But, there have been few studies about the benefits of the lower consumption of coffee, and how it affects ones risk of type 2 diabetes. This is what this research paper was looking into. The research paper’s design was very thorough for the steps needed to carry out a successful prospective cohort on younger to middle aged U.S women. The data that was used was from the prospective nurses’ study that started in 1989. One of the questions that were asked that pertain to this study was caffeine intake, not just from coffee but from other sources such as soda or candy. This information was then used to estimate total daily intake of caffeine and was stratified into low, medium and high groups respectively. Body mass index (BMI) was also used in this study, as well as smoking and alcohol habits. Individuals that had a history of cancer or cardio vascular disease were left out of the analysis as well as people with a history of diabetes. If on a follow up questionnaire it was noted that diabetes had developed, a secondary questionnaire was sent out to verify the diagnosis and to see if the diabetes was from being pregnant. In the end over 88,000 women remained in the study for statistical analysis.

The results showed that coffee consumption did lower ones risk of type 2 diabetes, and the study was able to quantify the results for many consumption levels. After multivariable adjustments the Relative Risk (RR) for type two diabetes where (.87) for one cup of coffee per day, (.58) for 2-3 cups per day and (.53) for four or more cups per day. It was found that tea consumption was not substantially associated with a lower risk of type 2 diabetes. One result showed that the way the coffee was made did vary in caffeine content, and that a “Starbucks latte” type of drink has the lowest caffeine content. Another finding was that high coffee consumption was also linked to a higher risk that the individual in the study smoked and/or had a high level of alcohol intake. I think this is because if you have an addictive personality you are more likely to become addicted to stimulates/drugs.

In looking at the data I did not see any mistakes that the researchers concluded; the number of individuals left in the study was large enough to be statically valid. The confidence intervals were very reliable and ranges from P=.05-.0001 so the RR that were calculated were valid. Some of the possible mistakes that could have entered this study were that people could have not told the truth about weight, but I believe this to be minimal because the population in question were medical professionals, and I think they would care less about weight than the normal population. Something that was not noted was if the follow up questionnaires monitored exercise. This is important because if the person changed their exercise habits it would lower the persons risk for type 2 diabetes, in addition to their coffee intake.

This study is important in the sense that it shows people that drinking coffee does lower ones risk for type 2 diabetes, and you don’t have to drink excessive amounts of coffee for the benefits. This information should be used carefully, because drinking too much coffee is not a good idea due to the health effects on the heart, such as rapid heart rate. In the end I think it will prove that drinking a moderate (2-3 cups) amount of coffee will help save lives from type 2 diabetes deaths.

Rob M. Dam PHD. (2006). Coffee, Caffeine, and Risk of Type 2 Diabetes. Diabetes Care, 29(2) 398-403

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