Writing in Nutrition Journal, the researchers from Mahidol University, Silpakorn University, and Srinakharinwirot University, said that this could be due to curcumin’s anti-inflammatory effect and its role in maintaining healthy beta-cell (β-cell) functions.
Beta-cells, located in the pancreas, are involved in the synthesis, storage, and release of insulin.
Using the homeostasis model assessment (HOMA-β), the researchers also showed an improvement in β-cell function in individuals who took curcumin during the study.
A total of 272 type II diabetes aged 35 and above participated in the study.
They were randomised to take either 1,500mg of curcumin per day or placebo for 12 months.
All study materials were manufactured by the Thailand Government Pharmaceutical Organization.
During the study, all participants also received metformin, and no other diabetic medications to control their blood glucose levels.
They were also advised to take low-glycaemic index foods, such as legumes and whole grains, increase their dietary fibre intake, and engage in at least 150 min of moderate-intensity aerobic exercise weekly.
The primary goal of the study is the find out how curcumin supplementation could affect β-cells functions. This is determined by measuring Homeostasis Model Assessment of beta-cell function (HOMA-β) and insulin levels, which are related to β-cell functions.
Changes in body weight, body mass index, fasting plasma glucose, insulin, insulin resistance etc were also measured as secondary goals.
Findings showed that curcumin supplementation has significantly improved HOMA-β at ninth and 12th month of the study.
A higher HOMA-β value suggests better β-cell functionality.
In this case, HOMA-β value in the intervention group had increased from the baseline of 113.26 to 123.73 at the ninth month and further went up to 136.20 at the 12th month.
This however, dropped from the baseline of 108.44 to 108.32 at the ninth month and further down to 105.19 at the 12th month for the placebo group.
“We found that the curcumin intervention improved β-cell functions, indicated by increased HOMA-β.
“HOMA-β is a straightforward method that is less invasive and more cost-effective compared to other techniques, making it applicable in various research settings and clinical practice,” said the researchers, although they also cautioned that the accuracy depended on several assumptions, such as steady-state conditions of glucose and insulin.
The higher HOMA-β value in the intervention group was also accompanied by improved insulin levels.
For them, insulin levels dropped significantly dropped from the baseline of 17.47 uU/ml to 17.06 uU/ml at the third month and further down to 16.05 uU/ml at the 12th month.
In contrast, insulin levels of the placebo group went up from the baseline of 16.96 uU/ml to 18.54 uU/ml by the end of the study.
Secondary findings
Aside from insulin levels, curcumin supplementation also significantly reduced fasting blood glucose and glycated haemoglobin (HbA1c) from baseline.
Fasting blood glucose, for instance, fell from 123.65 mg/dl to 115.49 mg/dl post-intervention, while glycated haemoglobin dropped from 6.28 per cent to 6.12 per cent – both results were significantly lower than the placebo group.
The placebo group’s fasting blood glucose had instead increased from 125.08 mg/dl to 130.71 mg/dl, while glycated haemoglobin had also gone up from 6.26 per cent to 6.47 per cent.
In a similar fashion, body weight of the intervention group was reduced but no noticeable difference was seen in the placebo group.
Body weight of the intervention group dropped from 69.92kg to 66.10kg by the end of the study, while that of the placebo group hovered at the 69kg to 69.5kg range throughout the study.
Based on this finding, the researchers said that there was a correlation between body weight and glycated haemoglobin levels.
“Our findings revealed a significant positive correlation between changes in body weight and HbA1c levels in the curcumin group, indicating that weight loss is associated with improvements in glycated haemoglobin (HbA1c).
“This association was particularly pronounced among individuals with T2DM. These indicated that curcumin treatment may result in better β-cell function in type 2 diabetes patients,” said the researchers.
In addition, the intervention group saw a significant increase in serum levels of adiponectin – an anti-inflammatory cytokine which is associated with a lower risk of type II diabetes.
Adverse effects
Mild adverse effects such as abdominal pain, diarrhoea, and headache were reported. However, no dropouts were seen due to these effects.
The researchers also said they found no significant differences in the amounts of liver enzymes aspartate aminotransaminase (AST), alanine aminotransferase (ALT), and creatinine between the intervention and placebo group.
This means that no adverse effects that could affect kidney and liver functions were seen.
“Taken together, these results indicated that curcumin extract can be used for intervention, at least for a period of 12 months, without serious adverse effect,” said the researchers.
The study was jointly supported by the Thailand Research Fund and Thai Traditional Medical Knowledge Fund.
Source: Nutrition Journal
Curcumin extract improves beta cell functions in obese patients with type 2 diabetes: a randomized controlled trial
DOI: 10.1186/s12937-024-01022-3
Authors: Yaikwawong M, Jansarikit L, Jirawatnotai S, Chuengsamarn S.
