Effect of vitamin E intake on glycemic control and insulin resistance in diabetic patients: an updated systematic review and meta-analysis of randomized controlled trials

Abstract

Since a 2014 meta-analysis, several randomized controlled trials (RCTs) evaluating the effect of vitamin E intake on glycemic indices and insulin resistance in adults with diabetes have reached inconsistent conclusions. Therefore, we updated the previous meta-analysis to summarize the current evidence in this regard. Online databases including PubMed, Scopus, ISI Web of Science, and Google Scholar were searched to identify relevant studies published up to September 30, 2021, using relevant keywords. Random-effects models were used to obtain overall mean difference (MD) comparing vitamin E intake with a control group. In total, 38 RCTs with a total sample size of 2171 diabetic patients (1110 in vitamin E groups and 1061 in control groups) were included. Combining the results from 28 RCTs on fasting blood glucose, 32 RCTs on HbA1c, 13 RCTs on fasting insulin, and 9 studies on homeostatic model assessment for insulin resistance (HOMA-IR) showed a summary MD of -3.35 mg/dL (95% CI: -8.10 to 1.40, P = 0.16), -0.21% (95% CI: -0.33 to -0.09, P = 0.001), -1.05 µIU/mL (95% CI: -1.53 to -0.58, P < 0.001), and -0.44 (95% CI: -0.82 to -0.05, P = 0.02), respectively. This indicates a significant lowering effect of vitamin E on HbA1c, fasting insulin and HOMA-IR, while no significant effect on fasting blood glucose in diabetic patients. However, in subgroup analyses, we found that vitamin E intake significantly reduced fasting blood glucose in studies with an intervention duration of < 10 weeks. In conclusion, vitamin E intake has a beneficial role in improving HbA1c and insulin resistance in a population with diabetes. Moreover, short-term interventions with vitamin E have resulted in lower fasting blood glucose in these patients. This meta-analysis was registered in PROSPERO with code CRD42022343118.

Inverse Correlation of Superoxide Dismutase and Catalase with Type 2 Diabetes among Rural Thais

“…Moreover, our study revealed no clear associations of both vitamins A and E with T2D incidence. These findings are consistent with other studies, which showed no significantly different correlations between the vitamin A and E status and the risk of T2D [16,38,39]. Another explanation might be because of an adequate intake of both vitamins, which was found in our study groups.…”

“…Vitamin E (α-tocopherol) is an important natural lipophilic antioxidant. It helps ameliorate high blood glucose concentrations [16]. Vitamin E levels are also reportedly lower in patients with T2D than in those without T2D; supplementation of this vitamin could delay diabetic complications because it aids in reducing ROS formation [14,16].…”

Translational Research on Bee Pollen as a Source of Nutrients: A Scoping Review from Bench to Real World

“…A countless number of studies unveiling the antidiabetic properties, including early preventive, disease course modifying, and complication limiting effects, of individual nutrients and phytochemicals that are ubiquitously present in BP from different botanical and geographical origins have been published so far. This includes, for example, nutrients including vitamins such as groups B [ 241 , 242 , 243 ], C [ 244 , 245 , 246 ], D [ 247 , 248 , 249 ], and E [ 128 , 250 , 251 ], oligo-elements and other minerals [ 252 , 253 , 254 ], and lipids such as unsaturated fatty acids [ 255 , 256 , 257 ] and phytosterols [ 63 , 258 , 259 ], as well as other phytochemicals including polyphenols such as phenolic acids, flavonoids, and stilbenes (very recent and comprehensive reviews of preclinical and clinical evidence can be found in [ 260 , 261 , 262 , 263 , 264 , 265 , 266 ]). Despite the substantial amount of experimental and clinical evidence of all these BP compounds in the complex pathophysiology of diabetes and in its interaction with other comorbidities, the possible synergistic potential and real clinical outcome of these compounds, which are always combined in BP, have generally been omitted in research and must be further studied by in vivo experiments, and subsequently verified and objectively assessed by clinical studies.…”

Can Nutrition Contribute to a Reduction in Sarcopenia, Frailty, and Comorbidities in a Super-Aged Society?

“…Appropriate management procedure for malnutrition in diabetes mellitus patients has not still been established. Zn [130,131], vitamin E [132], folate [133], and L-arginine [134,135] supplementation and fiber-rich diets [136] have been suggested to potentially improve blood glucose control and insulin resistance. The reason why L-arginine improved glycemic control and insulin resistance is not clear in detail.…”

“…Zinc (Zn) [130,131], vitamin E [132], folate [133], and L-arginine [134,135] supplementation and fiber-rich diets [136] may improve glycemic control and insulin resistance (IR) in type 2 diabetes mellitus patients. The Mediterranean diet may improve glycemic control [137] and reduce cardiovascular diseases risk [137,138].…”