Coffee is one of the most widely consumed beverages and ongoing research suggests that coffee consumption may help to reduce the risk of developing Type 2 diabetes. There is currently no evidence to suggest that individuals with diabetes need to avoid coffee.
Type 1 Diabetes
Type 1 diabetes, also sometimes known as ‘early onset’ or ‘juvenile’ diabetes, generally develops before the age of 40, usually during the teenage years. This form of diabetes is insulin dependent and cannot therefore be controlled by diet alone.
In relation to Type 1 diabetes, published research has shown that a modest amount of caffeine can increase awareness of the warning symptoms associated with the onset of a hypoglycaemic episode, and thus allow the patient to take action to avoid such an event 1.
Type 2 Diabetes
Type 2 diabetes is a condition that currently affects nearly three million people in the UK 2. It is estimated that this will increase to five million by 2025 2. Type 2 diabetes used to be called 'maturity onset' diabetes because it usually appears in middle-aged or elderly people, although it is increasingly affecting younger people 3. The main causes are that the body no longer responds normally to its own insulin (insulin resistance) and/or that the body does not produce enough insulin (pancreatic insulin deficiency). Type 2 diabetes may be controlled by diet alone or by diet in combination with medication.
Published research has concluded that long-term coffee consumption is associated with a statistically significantly lower risk for Type 2 diabetes 4,5,6, with 3 to 4 cups a day associated with an approximate 25% lower risk compared to consuming none or less than two cups per day 7, and that coffee drinking has a graded inverse association with the risk of Type 2 diabetes 8. A study published in Diabetologia in April, 2014, found increasing coffee consumption by more than one cup per day over a four year period lowered the risk of developing Type 2 diabetes by 11% in the subsequent four years. Decreasing coffee intake by more than one cup per day may increase the risk of diabetes by 17%.9 In addition, the study found that consuming three or more cups of coffee per day lowered the risk of developing Type 2 diabetes by 37%.9
While the mechanisms behind this are not clear at present, there are a number of potential physiological processes that may lead to the reduced risk of Type 2 diabetes, such as caffeine’s effect on glucose metabolism 10 and effect on insulin sensitivity 11. Research into the relationship between coffee drinking and the development of Type 2 diabetes continues and many strong studies have been published that add considerable weight to this area of research 12,13.
Further research is needed to confirm the mechanisms of action involved in the potentially protective effect of coffee consumption against diabetes, though findings to date are very encouraging.
In addition, coffee drinkers who have diabetes can continue to enjoy coffee confident in the knowledge that moderate coffee consumption - up to four or five cups per day (400mg of caffeine) - can contribute to a healthy, balanced diet and may confer health benefits. Pregnant women should however moderate their intake following the guidelines issued by the NHS to 200mg caffeine per day (equal to two to three cups of coffee) from all sources.
1. Watson. (2000) Diabetes Care, Volume 23.
2. Diabetes UK. (2013) http://www.diabetes.org.uk/About_us/What-we-say/Statistics/Diabetes-in-the-UK-2013-Key-statistics-on-diabetes/
3. IMAGE. (2010) Available at: www.image-project.eu/Default.aspx?id=0
4. Van Dam R.M. et al. (2002) Lancet, 360:1477-1478.
5. Zhang Y. et al. (2011) Nutrition, Metabolism & Cardiovascular Diseases: 21(6):418-423.
6. Muley A. et al. (2012) Current Diabetes Reviews; 8:162-168.
7. Huxley R. et al. (2009) Arch Intern Med 169:2053-63.
8. Tuomilehto. JAMA, Volume 291, 2004.
9. Bhupathiraju, S. N. et al. (2014) Diabetologia, published online ahead of print.
10. Zaharieva D.P. & Riddell M.C. (2013) Applied Physiology, Nutrition & Metabolism, Aug;38(8):813-22.
11. Rebelllo S.A. et al. (2011) Nutrition. 10:61.
12. Hiramatsu T. et al. (2012) Clinical Chemistry and Laboratory Medicine, 2012; 25:1-7.
13. Wedick N.M. et al. (2011) Nutrition Journal, 2011; 10:93.