- Turmeric (Curcuma longa)
- Type 2 Diabetes
Re: Curcuminoid Extract Lowered the Risk for Type 2 Diabetes Mellitus Development in Prediabetic Subjects
S, Rattanamongkolgul S, Luechapudiporn R, Phisalaphong C, Jirawatnotai S.
Curcumin extract for prevention of type 2 diabetes. Diabetes Care. July 6, 2012;[epub ahead of print]. doi:
than 300 million people worldwide have type 2 diabetes mellitus (T2DM), and its
prevalence continues to increase. Persons with prediabetes (having blood
glucose levels higher than normal but not high enough to be diagnosed as
diabetes) can often prevent the development of the disease by making lifestyle
changes, but those changes are often challenging. Effective therapeutic agents,
with relatively low cost and low toxicity, are needed to control the
progression of the disease. Curcumin, the principal curcuminoid in turmeric (Curcuma longa), has been shown to
possess anti-inflammatory and antidiabetic properties. These authors conducted
a randomized, double-blind, placebo-controlled trial to determine the
effectiveness of a curcuminoid extract in preventing the development of T2DM.
12-month trial was conducted at the HRH Princess Maha Chakri Sirindhorn Medical
Center of Srinakharinwirot University in Nakornnayok, Thailand. Eligible
subjects were instructed to follow the same protocols for diet and exercise for
3 months after enrollment while awaiting randomization. Standard lifestyle
recommendations were provided, and all subjects were counseled one-on-one on
the importance of a healthy lifestyle.
aged 35 years and older with prediabetes, as defined by the American Diabetes
Association (ADA) guidelines, were included. Eligible subjects had at least 1
of these 3 criteria: fasting plasma glucose (FPG) between 100 mg/dL and 124
mg/dL; an oral glucose tolerance test (OGTT) at 2 hours post-glucose load
between 140 mg/dL and 199 mg/dL; and a glycated hemoglobin (HbA1c)
range from 5.7% to 6.4%.
237 subjects (with 3 dropouts after randomization) were randomly assigned to
either the curcumin-treated group (n=118) or the placebo-treated group (n=116).
Baseline characteristics were similar between the 2 groups.
subjects were instructed to take 3 capsules twice daily for 9 months. The
curcuminoid extract was prepared by extracting dried, powdered turmeric with
ethanol and removing the oleoresin. Each curcumin capsule contained 250 mg
curcuminoids (curcumin, demethoxycurcumin, and bisdemethoxycurcumin in a peak
ratio of 1:≤0.6:≤0.4, respectively). Compliance rates were determined by the
number of capsules the subjects returned at their follow-up visits at 3, 6, and
primary outcome was the number of subjects in the 2 groups diagnosed with T2DM
according to ADA guidelines. Secondary outcomes were changes in β-cell
functions (homeostasis model assessment [HOMA]-β, C-peptide, and
proinsulin/insulin ratio); insulin resistance (IR) by HOMA-IR; obesity;
abdominal obesity; and anti-inflammatory cytokine (adiponectin). β-cells store
and release insulin, which controls the level of glucose in the blood.
authors report that at all visits (months 3, 6, and 9), the diabetes-related
blood chemistries (FPG, OGTT at 2 h, and HbA1c) used to measure the
progression of the disease were all significantly lower in the curcumin-treated
group compared with the placebo-treated group (P<0.01). For example, at
month 9, FPG in the curcumin-treated group was 86.47 mg/dL (range=73-122 mg/dL)
compared with 108.21 mg/dL (range=80-138 mg/dL) in the placebo-treated group.
Mean baseline FPG values were 103.65 mg/dL in the curcumin-treated group and 103.24
mg/dL in the placebo-treated group.
their assessments of β-cell function, the authors discovered that HOMA-β in the
curcumin-treated group was increasingly elevated at all follow-up visits and
became statistically significant at month 9 (P<0.01). C-peptide levels were
significantly lower in the curcumin-treated group compared with the placebo-treated
group at 9 months (P<0.05). The proinsulin/insulin ratio showed a
nonsignificant, lower trend in the curcumin-treated group.
mean levels of HOMA-IR were lower in the curcumin-treated group than in the
placebo-treated group at all visits. The differences were significant at months
6 (P<0.05) and 9 (P<0.001). Adiponectin levels, unchanged in the
placebo-treated group, gradually increased at months 3 and 6 in the curcumin-treated
group and became significantly different than the placebo-treated group at
month 9 (P<0.05).
of the subjects in either group showed any change in kidney or liver functions.
A few subjects in the curcumin-treated group reported minor adverse side effects
such as itching, constipation, or vertigo.
authors report that none of the subjects in the curcumin-treated group
developed T2DM in regard to the primary outcome; however, the following numbers
of subjects in the placebo-treated group developed T2DM: 11 (9.5%) at month 6;
18 (15.5%) at month 9; and 19 (16.4%) at month 12.
authors note that the conversion rate of the placebo group was significantly
higher than that published in a "well-known" American study.1
They reasoned that the ethnicity of the subjects in their study may account for
the high conversion rate. They compared their results with those of a diabetes
study of a large Thai cohort2 that identified a set of strong risk
factors that accelerate the development of T2DM among the Thai population: old
age, high body mass index, high waist circumference, hypertension, and a family
history of diabetes. They found that the same factors influenced their study
and that their reported rate of development of T2DM was within the estimation
of the earlier study.2 "Therefore, we believe that the high
conversion rates found in the present study are a common characteristic of Thai
prediabetes," they write.
authors report that the ethanol-extracted curcuminoids used in this study
substantially and significantly prevented T2DM development in subjects with
prediabetes. They also found that the curcuminoid extract improved β-cell
of its benefits and safety, we propose that curcumin extract may be used for an
intervention therapy for the prediabetes population," they write.
Barrett-Connor E, Fowler SE, et al.; Diabetes Prevention Program Research
Group. Reduction in the incidence of type 2 diabetes with lifestyle
intervention or metformin. N Engl J Med.
2Aekplakorn W, Bunnag
P, Woodward M, et al. A risk score for predicting incident diabetes in the Thai
population. Diabetes Care. 2006;29(8):1872-1877.