Type 2 diabetes (T2D) is a disease in which blood glucose levels are too high. It typically starts with insulin resistance: a condition where cells don’t respond appropriately to insulin. The pancreas then produces more insulin to try and get the cells to respond, but it’s unable to sustain this heightened production over time, resulting in chronically high blood glucose levels.

Most people with T2D do not present with symptoms initially because symptoms develop slowly over several years. People who do present with symptoms may report increased thirst, urination, or hunger, fatigue, blurred vision, and/or numbness or tingling in the feet or hands.

There are three blood tests used to diagnose T2D: fasting plasma glucose, 2-hour plasma glucose during a 75-gram oral glucose tolerance test, and HbA1c (i.e., average plasma glucose levels over the past 3 months).^[1]

Initial pharmacotherapy generally starts with metformin, which is an older, safe and relatively inexpensive drug. Frequently, other medications are required to control glucose levels, such as sodium-glucose cotransporter-2 (SGLT2) inhibitors or glucagon-like peptide 1 receptor agonists (GLP-1 RA). These medications can be particularly beneficial in people at an increased risk of or with established cardiovascular or kidney disease.^[2] Up to 35% of people with T2D eventually require insulin to achieve their glycemic targets. Besides glucose-lowering medications, medications or procedures (i.e., metabolic surgery) that facilitate weight loss are also effective for improving glycemic control.

The supplement with the most potential for improving glycemic control is berberine, an alkaloid extract from various plants used in traditional Chinese medicine.^[3] Soluble fiber (e.g., psyllium) is another effective option.^[4]

Long-term excess energy intake leads to the accumulation of fat in the liver and pancreas that causes T2D, and calorie restriction can decrease intra-organ fat and put the disease into remission.^[5] There is some evidence that high intake of added fructose, in particular, raises the risk of T2D.^[6] However, any dietary pattern can be effective for treating and preventing T2D as long as it facilitates an energy deficit and promotes sustained weight loss.^[7]

An increase in physical activity is recommended alongside dietary changes to achieve significant weight loss. A combination of aerobic and resistance exercise seems to be best to maximize improvements in glycemic control and health benefits.^[8] In people with prediabetes, exercise and weight loss can reduce the risk of progression to T2D by 58%. Psychological interventions, like cognitive behavioral therapy and motivational interviewing, can also improve glycemic control.^[9]

The cause of T2D is multifactorial, based on genetic predisposition and environment. Obesity, inflammatory diet, and sedentary lifestyle all contribute to the risk of developing T2D. Abdominal obesity is a strong risk factor for T2D, and leads to the accumulation of more fat in the liver and pancreas than a person can tolerate, which results from long-term excess energy intake.^[5]