Supplementing antidiabetic drugs with micronutrients for glycemic control Original paper

Glycemic control is critical for preventing complications in people with type 2 diabetes (T2D).^[1][2] Meta-analyses of randomized controlled trials suggest that supplementing with certain nutrients can improve some parameters of glycemic control in people with T2D.^[3][4][5] However, the effect of add-on nutrient supplements (i.e., used alongside antidiabetic drugs) on glycemic control had yet to be investigated.

This meta-analysis of 119 randomized controlled trials examined the effect of adding nutrient supplements to antidiabetic therapies (e.g., metformin, insulin) on glycemic control in people with T2D.

Nine nutrient supplements were analyzed:

• Vitamin D (29 studies; 400–6,000 IU/day)
• Omega-3 fatty acids (26 studies; 1–12 grams/day)
• Vitamin E (21 studies; 200–1,600 IU/day),
• Chromium (16 studies; 200–1,000 micrograms/day)
• Vitamin C (12 studies; 200–1,000 milligrams/day)
• Coenzyme Q10 (CoQ10; 11 studies; 150–200 milligrams/day)
• Zinc (5 studies; 30–240 milligrams/day)
• Alpha-lipoic acid (3 studies; 300–800 milligrams/day)
• Selenium (2 studies; 200 micrograms/day).

The outcomes assessed were HbA1c, fasting blood glucose, and HOMA-IR.

Chromium improved HbA1c (−0.39%), fasting blood glucose (−16.30 mg/dL), and HOMA-IR (−2.48). The effect of chromium was greater in participants with an HbA1c ≥ 8%, and chromium picolinate was the most effective formulation.

Additionally, vitamin C improved HbA1c (−0.37%) and fasting blood glucose (−11.96 mg/dL); CoQ10 improved HbA1c (−0.23%) and fasting blood glucose (−8.84 mg/dL); vitamin E improved HbA1c (−0.23%) and HOMA-IR (−0.37); and omega-3 fatty acids improved HbA1c (−0.26%).

There was moderate heterogeneity in the majority of the analyses, and the researchers were unable to identify the causes of heterogeneity in some of these, which reduces confidence in the findings.