Can curcumin and zinc supplements improve prediabetes?

This trial looked at how zinc and curcumin supplements affected people with prediabetes. It found that these supplements improved blood sugar and sensitivity to insulin.

Prediabetes is a condition in which the amount of glucose (sugar) in the blood is starting to become higher than normal. Prediabetes increases the risk of developing full-blown type 2 diabetes (T2D), as well as other health conditions such as heart disease.

The hormone insulin is responsible for lowering blood glucose. Insulin is released from the pancreas when the level of blood glucose increases, such as after eating sugar or other carbohydrates. When insulin levels are often high, the body can become less sensitive to this hormone. This resistance to insulin is a key part of prediabetes. In response to insulin resistance, the pancreas starts to produce more insulin to control blood sugar. Unfortunately, this can increase insulin resistance. Eventually, the beta-cells of the pancreas, where insulin is produced, can become overly stressed. They can lose function and no longer secrete insulin as well. This beta-cell exhaustion contributes to developing T2D.

There is interest in supplements to improve insulin sensitivity and blood glucose control for people with prediabetes. Curcumin is a bright yellow antioxidant found in the turmeric plant. Tumeric, a relative of ginger, is used in both Traditional Chinese and Ayurvedic medicine. Curcumin reduces inflammation. A few studies have found that curcumin may support glucose control for people with T2D.

Zinc is an essential nutrient which plays a role in how insulin works. People with prediabetes have low levels of zinc. It is not clear whether curcumin and/or zinc can benefit people with prediabetes.

This clinical trial included 84 people with prediabetes. All of the participants were also overweight or obese. They were randomly assigned to one of four groups: zinc, curcumin, zinc & curcumin (ZC), or control. The zinc group took both a daily zinc supplement and a placebo (inactive pill) which looked similar to the curcumin supplement. Similarly, participants took placebos instead of any supplements their group did not take. The control group served as a comparison and took two placebos. All of the participants were also given diet and exercise advice. The study lasted for 90 days.

The curcumin, zinc, and ZC groups all had significantly more improvement in blood sugar control than the control group. This was true for blood glucose levels both fasting and after eating. The three treated groups all had significantly lower insulin levels after 90 days, whereas the control group did not. The treated groups also had improved glycated hemoglobin (HbA1c), a measure of average blood glucose control over 2-3 months.

After adjusting for other factors, the treated groups also had significantly improved insulin sensitivity.

All four of the groups lost weight over the course of the trial. However, the zinc and ZC groups had significantly more improvement in body mass index (BMI) than the control group. This was significant even after adjusting for exercise.

This trial found that zinc and/or curcumin can improve blood glucose control and sensitivity to insulin for people with prediabetes. It also found that zinc improved body weight.

All of the participants were following a low-calorie diet over the course of the study, which may impact the effect of these supplements. The number of participants was very small. Larger studies are needed.

Talk to your doctor or nutritionist about all of your medicines and supplements. Ask whether zinc or curcumin would be beneficial for you.