Reading Time: 4 minutes

Type 2 diabetes, commonly referred to as diabetes mellitus, is a condition that prevails over a lifetime. The condition is distinguished by elevated levels of glucose in the blood. Type 2 diabetes generally has an onset in middle or late adulthood. Its occurrence is much more common than type 1 diabetes.[1]

Medications, proper diet and exercise are essential in controlling the levels of glucose in blood.[2] Several studies emphasise the role of coffee in reducing the risk of type 2 diabetes.[3] This article will discuss the relationship between coffee and type 2 diabetes along with the general health effects of coffee consumption.

What is type 2 diabetes?

The pancreas (an organ in abdomen) produces insulin when it senses the presence of glucose or when the body breaks down food into glucose.[2] Insulin is responsible for carrying glucose into the cells.[1] In type 2 diabetes, either the pancreas does not secrete sufficient insulin or the insulin is unable to carry out its functions properly.[2] There is an unhealthy accumulation of glucose in the blood vessels in a person with diabetes, which results in elevated blood glucose levels.[1] Diabetes can lead to complications of other organs such as eyes, kidneys and nerves.[2]

Symptoms of type 2 diabetes are as follows:[2]

  • Increased thirst and hunger
  • Dry mouth
  • Dry and itchy skin
  • Frequent urination
  • Numbness of hands and feet
  • Blurred vision
  • Fatigue

How is drinking coffee linked to type 2 diabetes?

Coffee is a commonly used beverage globally.[4] It has several health effects on the people who have been consuming it for a long time. If you consume coffee, then it is better to be aware of the positive and negative effects of coffee on health. According to the studies carried out in various countries, high consumption of coffee substantially reduces the risk of type 2 diabetes.[5] Evidence shows that the type of coffee also may play a role in lowering the risk of developing type 2 diabetes.[5] Filtered coffee lowered the risk of type 2 diabetes as compared to boiled coffee, whereas decaffeinated coffee had an edge over caffeinated coffee.[4]

How does coffee lower the risk of developing type 2 diabetes?

After the compilation of observations made from the studies, scientists have proposed the mechanisms involved in lowering the risk of type 2 diabetes by consumption of coffee.[6] Scientists attributed the mechanisms to the various chemical ingredients in coffee as discussed below:[6,7]

  • Studies indicate that coffee contains a substantial amount of potassium, niacin, magnesium and antioxidants, which may have beneficial effects on the development of diabetes through its actions on the metabolism of glucose and insulin resistance (the inability of the body to respond to insulin). However, additional studies are needed to confirm the long-term effect of caffeine.[7]
  • Animal studies show that the chlorogenic acid present in caffeine increased the body’s sensitivity to insulin. It also has a beneficial effect on the metabolism of glucose and contributes to antioxidant activity, thereby reducing the oxidative stress responsible for type 2 diabetes.
  • Another compound known as lignan is commonly found in coffee and shows its positive effect on the metabolism of glucose through antioxidant activity. Scientists noticed fewer cases of type 2 diabetes in animals that were administered with lignan.
  • Coffee contains magnesium. A higher intake of magnesium also improved insulin secretion and liver function, thus reducing the risk of type 2 diabetes.[6]

Although coffee is associated with lowering the risk of type 2 diabetes, it is necessary to consider that the addition of sugar, syrups and milk to coffee can result in increased levels of carbohydrates and glucose, especially in people with diabetes.[8]

Are there any negative effects of coffee?

Caffeinated coffee can increase blood pressure. Studies have also demonstrated that caffeinated coffee can increase anxiety, disrupt sleep patterns and lead to restlessness. Coffee can produce acid reflux and be really bad on your stomach. Unfiltered coffee can also increase the cholesterol levels in your blood.[6,9] Evidence suggest that coffee may lead to bone loss in elderly women.[10]

The choice of an appropriate type of coffee may help you in avoiding the detrimental effects of coffee and lower the risk of type 2 diabetes. Although the research conducted to date suggests that drinking coffee can help in lowering the risk of diabetes, there is still a lot more work to be done on the components of coffee and their actions. Despite the positive effects of coffee, it may be too early to suggest that an increase in coffee consumption reduces the risk of developing type 2 diabetes.

You may choose the right type of coffee to lower the risk of diabetes, but it is better to seek medical advice before making coffee an integral part of your regular diet.


  1. Harvard Medical School. Type 2 diabetes mellitus [Internet]. [updated 2018 Dec; cited 2020 Jan 8]. Available from:
  2. Cleveland Clinic. Diabetes mellitus: an overview: management and treatment. [Internet]. [updated 2018 Oct 2; cited 2020 Jan 8]. Available from:
  3. Harvard Medical School. Coffee may help reduce type 2 diabetes risk, says Harvard research [Internet]. [updated 2014 Jun; cited 2020 Jan 8]. Available from:
  4. Muley A, Muley P, Shah M. Coffee to reduce risk of type 2 diabetes?: A systematic review. Curr Diabetes Rev. 2012;8:162-8.
  5. van Dam RM, Hu FB. Coffee consumption and risk of type 2 diabetes. A systematic review. JAMA. 2005;294(1):97-104.
  6. van Dam RM. Coffee and type 2 diabetes: from beans to beta-cells. Nutr Metab & Cardiovas. 2006;16:69-77.
  7. Salazar-Martinez E, Willett WC, Ascherio A, Manson JE, Leitzmann MF, Stampfer MJ. Coffee consumption and risk for type 2 diabetes mellitus. Ann Intern Med. 2004;140:1-8.
  8. Harvard TH Chan School of Public Health. The nutrition source. Coffee [Internet]. [cited 2020 Jan 8]. Available from:
  9. AARP. Caffeine for your health – too good to be true? [Internet]. [cited 2020 Jan 8]. Available from:
  10. Pimentel GD, Zemdeg JCS, Theodoro JA, Mota JF. Does long-term coffee intake reduce type 2 diabetes mellitus risk? Diabetol Metab Syndr. 2009;1(6). doi:10.1186/1758-5996-1-6.

Loved this article? Don't forget to share it!

Disclaimer: The information provided in this article is for patient awareness only. This has been written by qualified experts and scientifically validated by them. Wellthy or it’s partners/subsidiaries shall not be responsible for the content provided by these experts. This article is not a replacement for a doctor’s advice. Please always check with your doctor before trying anything suggested on this article/website.