Is there evidence to support the effectiveness and safety of nutrient supplementation for control of blood glucose and management of insulin resistance in type 2 diabetes?

This review analyzed the effectiveness and safety of nutrient supplements for the control of blood glucose and insulin resistance in patients with type 2 diabetes (T2D). The authors concluded that there is currently a lack of sufficient clinical evidence to support the use of nutrient supplements for blood glucose control and improved insulin resistance in these patients.

T2D is associated with insufficient insulin production (insulin deficiency) or an inability of the body tissues to respond to insulin (insulin resistance). As a result, patients with T2D are unable to achieve their blood glucose targets based on glycated hemoglobin measurements (HbA1c). HbA1c levels indicate the average blood glucose over 2-3 months.

Diet, weight management, and physical activity play an important role in the control of high blood glucose. Nutrient supplements such as vitamins, minerals, prebiotics, probiotics, fatty acids, and amino acids are used by many individuals with T2D. However, there is a lack of clinical evidence to indicate clear benefits for their use in the management of T2D.

This review analyzed 13 studies on adults with T2D that used nutrient supplements. Nutrient supplements used in the studies included vitamin C, chromium, probiotics, zinc, magnesium, polyphenols, polyunsaturated fatty acids (Ω-3 PUFAs), vitamin D, and folate. Measurements on glycemic control, insulin sensitivity, and secretion were assessed.

There was very low certainty of evidence that the use of chromium, vitamin C, Ω-3 PUFAs, or vitamin D resulted in improved HbA1c levels compared to placebo. Probiotics use resulted in better HbA1c values compared to placebo. Compared to a placebo, the use of magnesium, zinc, vitamin C, probiotics, and polyphenols was better for the control of fasting blood glucose. Compared to a placebo, vitamin D was better at improving insulin resistance.

The review indicated a low certainty of evidence for the use of nutrient supplements in the management of T2D.

The review analyzed the results of several studies that in turn, may not have used the best selection strategies for inclusion. As a result, the certainty of the conclusions drawn from the review is unclear. Large randomized trials are needed to further evaluate nutrient supplements in patients with T2D.