Cinnamon Improves Glucose and Lipids of People With Type 2 Diabetes

Abstract

The objective of this study was to determine whether cinnamon improves blood glucose, triglyceride, total cholesterol, HDL cholesterol, and LDL cholesterol levels in people with type 2 diabetes.
A total of 60 people with type 2 diabetes, 30 men and 30 women aged 52.2 +/- 6.32 years, were divided randomly into six groups. Groups 1, 2, and 3 consumed 1, 3, or 6 g of cinnamon daily, respectively, and groups 4, 5, and 6 were given placebo capsules corresponding to the number of capsules consumed for the three levels of cinnamon. The cinnamon was consumed for 40 days followed by a 20-day washout period.
After 40 days, all three levels of cinnamon reduced the mean fasting serum glucose (18-29%), triglyceride (23-30%), LDL cholesterol (7-27%), and total cholesterol (12-26%) levels; no significant changes were noted in the placebo groups. Changes in HDL cholesterol were not significant.
The results of this study demonstrate that intake of 1, 3, or 6 g of cinnamon per day reduces serum glucose, triglyceride, LDL cholesterol, and total cholesterol in people with type 2 diabetes and suggest that the inclusion of cinnamon in the diet of people with type 2 diabetes will reduce risk factors associated with diabetes and cardiovascular diseases.

Full text

Cinnamon Improves Glucose and Lipids
of People With Type 2 Diabetes
ALAM KHAN,
MS, PHD
1,2,3
MAHPARA SAFDAR,
MS
1,2
MOHAMMAD MUZAFFAR ALI KHAN,
MS, PHD
1,2
KHAN NAWAZ KHATTAK,
MS
1,2
RICHARD A. ANDERSON,
PHD
3
OBJECTIVE — The objective of this study was to determine whether cinnamon improves
blood glucose, triglyceride, total cholesterol, HDL cholesterol, and LDL cholesterol levels in
people with type 2 diabetes.
RESEARCH DESIGN AND METHODS — A total of 60 people with type 2 diabetes, 30
men and 30 women aged 52.2 ⫾ 6.32 years, were divided randomly into six groups. Groups 1,
2, and 3 consumed 1, 3, or 6 g of cinnamon daily, respectively, and groups 4, 5, and 6 were given
placebo capsules corresponding to the number of capsules consumed for the three levels of
cinnamon. The cinnamon was consumed for 40 days followed by a 20-day washout period.
RESULTS — After 40 days, all three levels of cinnamon reduced the mean fasting serum
glucose (18 –29%), triglyceride (23–30%), LDL cholesterol (7–27%), and total cholesterol (12–
26%) levels; no significant changes were noted in the placebo groups. Changes in HDL choles-
terol were not significant.
CONCLUSIONS — The results of this study demonstrate that intake of 1, 3, or6gof
cinnamon per day reduces serum glucose, triglyceride, LDL cholesterol, and total cholesterol in
people with type 2 diabetes and suggest that the inclusion of cinnamon in the diet of people with
type 2 diabetes will reduce risk factors associated with diabetes and cardiovascular diseases.
Diabetes Care 26:3215–3218, 2003
T
he incidence of cardiovascular dis-
eases is increased two- to fourfold in
people with type 2 diabetes (1). Al-
though the causes of type 2 diabetes and
cardiovascular diseases are multifactorial,
diet definitely plays a role in the incidence
and severity of these diseases. The dietary
components beneficial in the prevention
and treatment of these diseases have not
been clearly defined, but it is postulated
that spices may play a role. Spices such as
cinnamon, cloves, bay leaves, and tur-
meric display insulin-enhancing activity
in vitro (2,3). Botanical products can im-
prove glucose metabolism and the overall
condition of individuals with diabetes not
only by hypoglycemic effects but also by
improving lipid metabolism, antioxidant
status, and capillary function (4). A num-
ber of medicinal/culinary herbs have been
reported to yield hypoglycemic effects in
patients with diabetes. Examples of these
include bitter melon, Gymnema, Korean
ginseng, onions, garlic, flaxseed meal, and
specific nutrients including ␣-lipoic acid,
biotin, carnitine, vanadium, chromium,
magnesium, zinc, and vitamins B
3
,E,and
K (5).
Rashwan (6) reported that supple-
mentation of the diet of rabbits with
fenugreek decreased total serum lipid
level. In rats, curry leaf and mustard seeds
decreased total serum cholesterol, LDL
cholesterol, and VLDL cholesterol and in-
creased HDL cholesterol levels (7) and re-
duced cholesterol, triglycerides, and
phospholipids in aorta, liver, and heart
(8). The LDL and VLDL fractions were
also decreased and the HDL fraction was
increased. Coriander seeds fed to rats con-
suming a high-fat diet led to decreased
LDL, VLDL, and total cholesterol and in-
creased HDL cholesterol (9). Zhang et al.
(10) reported that turmeric may also have
a role in reducing the risk of atherosclerosis.
Aqueous extracts from cinnamon
have been shown to increase in vitro glu-
cose uptake and glycogen synthesis and to
increase phosphorylation of the insulin
receptor; in addition, these cinnamon ex-
tracts are likely to aid in triggering the
insulin cascade system (11,12). Because
insulin also plays a key role in lipid me-
tabolism, we postulated that consump-
tion of cinnamon would lead to improved
glucose and blood lipids in vivo. There-
fore, this study was designed to determine
whether there is a dose response of cinna-
mon on clinical variables associated with
diabetes and cardiovascular diseases in
people with type 2 diabetes.
RESEARCH DESIGN AND
METHODS — This study was con-
ducted in the Department of Human Nu-
trition, NWFP Agricultural University,
Peshawar, Pakistan and was approved by
the Ethics Committee and Human Studies
Review Board of the University of Pesha-
war. Selection criteria for the study in-
cluded the following for people with type
2 diabetes: age ⬎40 years, not on insulin
therapy, not taking medicine for other
health conditions, and fasting blood glu-
cose levels between 7.8 and 22.2 mmol/l
(140–400 mg/dl). A total of 60 individu-
als with type 2 diabetes, 30 men and 30
women, were selected for the study. The
mean age of the subjects was 52.0 ⫾ 6.87
years in the placebo groups and 52.0 ⫾
5.85 years in the groups consuming cin-
namon. The duration of diabetes was also
similar: 6.73 ⫾ 2.32 years for the placebo
group and 7.10 ⫾ 3.29 years for the cin-
namon groups. There was also an equal
number of men and women in the pla-
●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●
From the
1
Department of Human Nutrition, NWFP Agricultural University, Peshawar, Pakistan; the
2
Post
Graduate Medical Institute, Hayatabad Medical Complex, Peshawar, Pakistan; and the
3
Nutrients Require
-
ments and Functions Laboratory, Beltsville Human Nutrition Research Center, Beltsville, Maryland.
Address correspondence and reprint requests to Dr. Richard A. Anderson, Nutrient Requirements and
Functions Laboratory, Beltsville Human Nutrition Research Center, Bldg. 307, Rm. 224, Beltsville, MD
20705. E-mail: Anderson@307.bhnrc.usda.gov.
Received for publication 30 June 2003 and accepted in revised form 22 August 2003.
A table elsewhere in this issue shows conventional and Syste`me International (SI) units and conversion
factors for many substances.
© 2003 by the American Diabetes Association.
Clinical Care/Education/Nutrition
ORIGINAL ARTICLE
DIABETES CARE, VOLUME 26, NUMBER 12, DECEMBER 2003 3215

cebo and cinnamon groups. All subjects
were taking sulfonylurea drugs, i.e., glib-
enclamide; medications did not change
during the study.
Cinnamon (Cinnamomum cassia) cer-
tified by the Office of the Director, Re-
search and Development/Non-Timber
Forest Products, NWFP Forest Depart-
ment, Peshawar, Pakistan, was used in
this study. Cinnamon and wheat flour
were ground finely and put into capsules
(Mehran Traders Pharmaceutical Suppli-
ers, Peshawar, Pakistan). Each capsule
contained either 500 mg of cinnamon or
wheat flour. Both the cinnamon and pla-
cebo capsules were packaged in plastic
bags containing 40 capsules (1 g or two
capsules per day for 20 days), 120 cap-
sules (3 g or six capsules per day for 20
days), or 240 capsules (6 g or 12 capsules
per day for 20 days) and prepared for dis-
tribution to the subjects. When subjects
finished testing after the first 20 days, they
were given the second package of cap-
sules. Compliance was monitored by cap-
sule count and contact with the subjects.
Compliance was considered excellent and
all capsules were consumed.
The study was conducted for 60 days
with 60 individuals with type 2 diabetes
divided randomly into six equal groups.
Group 1 consumed two 500-mg capsules
of cinnamon per day, group 2 consumed
six capsules of cinnamon per day, and
group 3 consumed 12 capsules of cinna-
mon per day. Groups 4, 5, and 6 were
assigned to respective placebo groups,
which consumed a corresponding num-
ber of capsules containing wheat flour.
Subjects consumed their normal diets and
continued their medications throughout
the study. From days 41 to 60, no cinna-
mon or placebo was given. The 1-g dose
of cinnamon and placebo was spread over
the day as 0.5 g (one capsule) after lunch
and 0.5 g after dinner. The 3-g and 6-g
doses of cinnamon and placebo were
spread over the day as 1 g (two capsules)
and 2 g (four capsules) after breakfast,
lunch, and dinner, respectively. The sub-
jects were instructed to take the capsules
immediately after meals.
On days 0, 20, 40, and 60, ⬃5mlof
fasting blood was collected from each
subject. Blood samples were transferred
to sterilized centrifuge tubes and allowed
to clot at room temperature. The blood
samples were centrifuged for 10 min in a
tabletop clinical centrifuge at 4,000 rpm
for serum separation. Serum samples
were stored in a freezer at 0°C for later
analyses.
Glucose level was determined using
an autoanalyzer (Express Plus; Ciba
Corning Diagnostics, Palo Alto, CA). Tri-
glyceride levels were determined by the
enzymatic colorimetric method of
Werner et al. (13) using an autoanalyzer
(Express Plus; Ciba Corning) and an
Elitech kit (Meditek Instrument, Pesha-
war, Pakistan). Cholesterol levels were
determined by enzymatic colorimetric
method of Allain et al. (14) using the same
autoanalyzer. Chylomicrons, VLDL, and
LDL were precipitated by adding phos-
photungstic acid and magnesium ions to
the sample. Centrifugation left only the
HDL in the supernatant (15). LDL choles-
terol was calculated by dividing the trig-
lycerides by 5 and subtracting the HDL
cholesterol (16).
Two-way ANOVA and randomized
complete block design were used for sta-
tistical analysis (17). Values are means ⫾
SD.
RESULTS — The addition of 1, 3, or
6 g of cinnamon to the diet led to signifi-
cant decreases in serum glucose levels af-
ter 40 days. Values after 20 days were
significantly lower only in the group re-
ceiving6gofcinnamon (Table 1). At the
levels tested, there was no evidence of a
dose response because the response to all
three levels of cinnamon was similar. De-
creases ranged from 18 to 29%. After the
subjects no longer consumed the cinna-
mon for 20 days, glucose levels were sig-
nificantly lower only in the group
consuming the lowest level of cinnamon.
Glucose values in the three placebo
groups were not significantly different at
any of the time points.
The consumption of cinnamon also
led to a time-dependent decrease in se-
rum triglyceride levels at all amounts of
cinnamon tested after 40 days (Table 2).
Values after 20 days were significantly
Table 1—Effects of cinnamon on glucose levels in people with type 2 diabetes
Group*
Doses of
cinnamon
(g/day)
Fasting serum glucose level (mmol/l)†
Before
cinnamon
intake During cinnamon intake
After
cinnamon
intake
Day 0 Day 20 Day 40 Day 60
1 1 11.6 ⫾ 1.7
a
10.5 ⫾ 1.8
ab
8.7 ⫾ 1.6
c
9.7 ⫾ 1.4
bc
2 3 11.4 ⫾ 1.2
a
9.9 ⫾ 1.1
ab
9.4 ⫾ 1.1
b
9.9 ⫾ 1.6
ab
3 6 13.0 ⫾ 1.4
a
10.2 ⫾ 1.3
bc
9.2 ⫾ 1.5
c
11.4 ⫾ 1.8
ab
4 Placebo 1 12.2 ⫾ 1.0
a
12.7 ⫾ 0.8
a
12.4 ⫾ 1.1
a
12.6 ⫾ 1.0
a
5 Placebo 2 12.4 ⫾ 1.0
a
11.8 ⫾ 0.9
a
12.7 ⫾ 1.0
a
12.6 ⫾ 1.3
a
6 Placebo 3 16.7 ⫾ 1.4
a
16.7 ⫾ 1.6
a
16.8 ⫾ 1.7
a
17.0 ⫾ 1.3
a
Data are means ⫾ SD. *Ten individuals in each group; †means followed by different superscript letters in the
same row are significantly different at P ⬍ 0.05.
Table 2—Effects of cinnamon on triglyceride levels in people with type 2 diabetes
Group*
Doses of
cinnamon
(g/day)
Fasting serum triglyceride level (mmol/l)†
Before
cinnamon
intake During cinnamon intake
After
cinnamon
intake
Day 0 Day 20 Day 40 Day 60
1 1 2.25 ⫾ 0.35
a
1.92 ⫾ 0.18
ab
1.57 ⫾ 0.21
b
1.67 ⫾ 0.21
b
2 3 2.75 ⫾ 0.30
a
2.74 ⫾ 0.49
a
2.01 ⫾ 0.36
b
2.16 ⫾ 0.52
b
3 6 2.48 ⫾ 0.39
a
1.81 ⫾ 0.28
b
1.91 ⫾ 0.30
b
2.07 ⫾ 0.32
ab
4 Placebo 1 2.31 ⫾ 0.32
a
2.38 ⫾ 0.34
a
2.50 ⫾ 0.30
a
2.45 ⫾ 0.32
a
5 Placebo 2 2.38 ⫾ 0.29
a
2.42 ⫾ 0.31
a
2.39 ⫾ 0.28
a
2.21 ⫾ 0.29
a
6 Placebo 3 2.55 ⫾ 0.34
a
2.66 ⫾ 0.38
a
2.52 ⫾ 0.40
a
2.65 ⫾ 0.35
a
Data are means ⫾ SD. *Ten individuals in each group; †means followed by different superscript letters in the
same row are significantly different at P ⬍ 0.05.
Cinnamon decreases glucose and lipids
3216 DIABETES CARE, VOLUME 26, NUMBER 12, DECEMBER 2003

lower only in the group consuming6gof
cinnamon per day. Decreases after 40
days of cinnamon consumption ranged
from 23 to 30%. These data indicate that
consumption of cinnamon for ⬎20 days
was more beneficial than shorter use for
reduction of triglyceride levels in people
with type 2 diabetes. The mean fasting
serum triglyceride levels of the subjects
who consumed1gor3gofcinnamon per
day for 40 days followed by 20 days of not
consuming cinnamon were still signifi-
cantly lower than the mean fasting serum
triglyceride levels of the same groups at
the beginning of the study. Decreases in
the 6-g group were no longer significant.
There were no changes in triglyceride lev-
els in any of the three placebo groups
(Table 2).
There were also significant decreases
in serum cholesterol levels in all three
groups consuming cinnamon, and no
changes were noted in the respective pla-
cebo groups (Table 3). Decreases were
significant after 20 days, and values were
similar after 40 days, except in the group
consuming 3 g per day, which continued
to decrease. These decreases in serum
cholesterol level ranging from 13 to 26%
were maintained even after not consum-
ing additional cinnamon for 20 days (Ta-
ble 3, last column).
Decreases in LDL were significant in
the 3- and 6-g groups after 40 days with
decreases of 10 and 24% (Table 4). De-
creases in the 1-g group were not signifi-
cant after 40 days but continued to
decline during the washout period and
were significant after 60 days (Table 4,
last column).
There were nonsignificant changes in
HDL in the subjects consuming 1 or6gof
cinnamon for 40 days. Decreases in the
3-g group were significant after 20 days.
These values remained relatively un-
changed after the 20-day washout period.
CONCLUSIONS — This study dem-
onstrates effects of low levels (1– 6 g per
day) of cinnamon on the reduction of glu-
cose, triglyceride, LDL cholesterol, and
total cholesterol levels in subjects with
type 2 diabetes. The study design serves
to replicate the results because there were
similar effects at the three doses tested. It
is not clear whether even less than1gof
cinnamon per day would also be benefi-
cial. The data are also reinforced by the
observation that there were no significant
changes in any of the placebo groups.
There were also no problems with com-
pliance or problems associated with the
consumption of ⱕ6 g of cinnamon per
day.
The mechanism of the effects of cin-
namon on glucose and blood lipids must
be determined. Symptoms of insulin re-
sistance include decreased stimulation of
muscle glycogen synthesis as well as de-
fects in glycogen synthase activity and
glucose uptake (18). In addition, altered
enzymatic activities, such as an increased
phosphatase activity and/or seryl phos-
phorylation of the insulin receptor sub-
strate by glycogen synthase kinase-3
(GSK-3), have also been shown to be in-
volved in some cases of type 2 diabetes
(19,20). Dephosphorylation of the recep-
tor ␤-subunit is associated with the deac-
tivation of its kinase activity and,
therefore, is associated with insulin signal
downregulation (21). Maximal phos-
phorylation of the insulin receptor is as-
sociated with increased insulin
sensitivity, which is associated with im-
proved glucose and lipid levels. Extracts
of cinnamon activated glycogen synthase,
increased glucose uptake, and inhibited
glycogen synthase kinase-3␤ (11,12). Ex-
tracts of cinnamon also activated insulin
receptor kinase and inhibited dephos-
phorylation of the insulin receptor, lead-
ing to maximal phosphorylation of the
insulin receptor (12). All of these effects
would lead to increased insulin sensitiv-
ity. We have shown that extracts of cin-
namon also function as potent
antioxidants, which would lead to addi-
tional health benefits of this substance
(unpublished data). Dhuley (22) showed
that cinnamon displays antioxidant activ-
ity in rats fed a high-fat diet.
The maintenance of lower serum glu-
cose and lipid levels, even when the indi-
viduals were not consuming cinnamon
for 20 days, denotes sustained effects of
cinnamon, indicating that cinnamon
would not need to be consumed every
Table 3—Effects of cinnamon on cholesterol levels in people with type 2 diabetes
Group*
Doses of
cinnamon
(g/day)
Fasting serum cholesterol level (mmol/l)†
Before
cinnamon
intake During cinnamon intake
After
cinnamon
intake
Day 0 Day 20 Day 40 Day 60
1 1 4.91 ⫾ 0.23
a
4.32 ⫾ 0.21
b
4.32 ⫾ 0.27
b
4.09 ⫾ 0.30
b
2 3 5.51 ⫾ 0.29
a
4.76 ⫾ 0.32
b
4.09 ⫾ 0.26
c
4.03 ⫾ 0.34
c
3 6 5.30 ⫾ 0.22
a
4.63 ⫾ 0.21
b
4.65 ⫾ 0.24
b
4.86 ⫾ 0.19
b
4 Placebo 1 4.58 ⫾ 0.28
b
4.67 ⫾ 0.35
b
4.58 ⫾ 0.31
b
4.78 ⫾ 0.31
a
5 Placebo 2 4.81 ⫾ 0.30
a
4.71 ⫾ 0.30
a
5.04 ⫾ 0.31
a
4.94 ⫾ 0.35
a
6 Placebo 3 5.51 ⫾ 0.41
c
5.69 ⫾ 0.44
ab
5.66 ⫾ 0.43
bc
5.84 ⫾ 0.42
a
Data are means ⫾ SD. *Ten individuals in each group; †means followed by different superscript letters in the
same row are significantly different at P ⬍ 0.05.
Table 4—Effects of cinnamon on LDL levels in people with type 2 diabetes
Group*
Doses of
cinnamon
(g/day)
Fasting serum LDL level (mmol/l)†
Before
cinnamon
intake During cinnamon intake
After
cinnamon
intake
Day 0 Day 20 Day 40 Day 60
1 1 2.66 ⫾ 0.12
a
2.28 ⫾ 0.15
b
2.48 ⫾ 0.10
ab
2.35 ⫾ 0.13
b
2 3 2.77 ⫾ 0.18
a
2.43 ⫾ 0.28
ab
2.04 ⫾ 0.19
bc
1.97 ⫾ 0.18
c
3 6 2.87 ⫾ 0.18
a
2.56 ⫾ 0.13
b
2.59 ⫾ 0.16
b
2.72 ⫾ 0.11
ab
4 Placebo 1 2.30 ⫾ 0.22
a
2.30 ⫾ 0.31
a
2.20 ⫾ 0.22
a
2.40 ⫾ 0.22
a
5 Placebo 2 2.56 ⫾ 0.25
a
2.40 ⫾ 0.22
a
2.66 ⫾ 0.27
a
2.79 ⫾ 0.27
a
6 Placebo 3 3.03 ⫾ 0.31
b
3.15 ⫾ 0.33
ab
3.28 ⫾ 0.34
a
3.36 ⫾ 0.37
a
Data are means ⫾ SD. *Ten individuals in each group; †means followed by different superscript letters in the
same row are significantly different at P ⬍ 0.05.
Khan and Associates
DIABETES CARE, VOLUME 26, NUMBER 12, DECEMBER 2003 3217

day. The levels of cinnamon tested in this
study, 1–6 g per day, suggest that there is
a wide range of cinnamon intake that may
be beneficial and that intake of ⬍1 g daily
is likely to be beneficial in controlling
blood glucose and lipid levels.
In conclusion, cinnamon reduced se-
rum glucose, triglyceride, total choles-
terol, and LDL cholesterol levels in people
with type 2 diabetes. Because cinnamon
would not contribute to caloric intake,
those who have type 2 diabetes or those
who have elevated glucose, triglyceride,
LDL cholesterol, or total cholesterol levels
may benefit from the regular inclusion of
cinnamon in their daily diet. In addition,
cinnamon may be beneficial for the re-
mainder of the population to prevent and
control elevated glucose and blood lipid
levels.
Acknowledgments— This project was
funded, in part, by the University Grants
Commission/NWFP Agricultural University,
Peshawar, Pakistan.
References
1. Raza A, Movahed A: Current concepts of
cardiovascular diseases in diabetes melli-
tus. Int J Cardiol 89:123–134, 2003
2. Khan A, Bryden NA, Polansky MM,
Anderson RA: Insulin potentiating factor
and chromium content of selected foods
and spices. Bio Trace Element Res 24:183–
188, 1990
3. Broadhurst CL, Polansky MM, Anderson
RA: Insulin-like biological activity of cu-
linary and medicinal plant aqueous ex-
tracts in vitro. J Agric Food Chem 48:849–
852, 2000
4. Bailey CJ, Day C: Traditional plant medi-
cines as treatments for diabetes. Diabetes
Care 12:553–564, 1989
5. Shapiro K, Gong WC: Natural products
used for diabetes. J Am Pharm Assoc 42:
217–226, 2002
6. Rashwan AA: Effects of dietary additions
of anise, fenugreek and caraway on repro-
ductive and productive performance of
New Zealand White rabbit does. Egypt J
Rabbit Sci 8:157–167, 1998
7. Khan BA, Abraham A, Leelamma S: Bio-
chemical response in rats to the addition
of curry leaf (Murraya koenigii) and mus-
tard seeds (Brassica juncea) to the diet.
Plant Foods Hum Nutr 49:295–299, 1996
8. Khan BA, Abraham A, Leelamma S: Influ-
ence of spices—Murraya koenigii and
Brassica juncea— on rats fed atherogenic
diet. J Food Sci 35:66 –68, 1998
9. Chithra V, Leelamma S: Hypolipidemic
effect of coriander seeds (Coriandrum sa-
tivum): mechanism of action. Plant Foods
Hum Nutr 51:167–172, 1997
10. Zhang WL, Liu DW, Wo XD, Zhang YH,
Jin MM, Ding ZS: Effects of Curcuma longa
on proliferation of cultured bovine
smooth muscle cells and on expression of
low-density lipoprotein receptor in cells.
Chinese Med J 112:308 –311, 1999
11. Imparl-Radosevich J, Deas S, Polansky
MM, Baedke DA, Ingebrutsen TS, Ander-
son RA, Graves DJ: Regulation of phos-
phorylase phosphatase (PTP-1) and
insulin receptor kinase by fractions from
cinnamon: implications for cinnamon
regulation of insulin signaling. Horm Res
50:177–182, 1998
12. Jarvill-Taylor KJ, Anderson RA, Graves
DJ: A hydroxychalcone derived from cin-
namon functions as a mimetic for insulin
in 3T3–L1 adipocytes. J Am Coll Nutr 20:
327–336, 2001
13. Werner M, Gabrielson DG, Eastman G:
Ultramicrodeterminations of serum tri-
glycerides by bioluminescent assay. Clin
Chem 21:268 –271, 1981
14. Allain CC, Poon LS, Chon CSG, Rich-
mond U, Fu PC: Enzymatic determina-
tion of total serum cholesterol. Clin Chem
20:470– 475, 1974
15. Lopes-Virella MF, Stone P, Ellis S, Cold-
well JA: Cholesterol determinations in
high density liproproteins separated by
three methods. Clin Chem 23:882–884,
1977
16. Friedewald WT, Levy RI, Fredrickson DS:
Estimation of the concentration of low
density lipoprotein cholesterol in plasma
without the use of the preparative ultra-
centrifuge. Clin Chem 18:499 –502, 1972
17. Freed RD: MSTAT-C With MGRAPH. Ver-
sion 2.00. East Lansing, MI, Michigan
State University, 1997
18. Cline GW, Oetersen KF, Krssak M, Shen
J, Hundal RS, Trajanoski Z, Inzucchi S,
Dresner A, Rothman DL, Shulman GI: Im-
paired glucose transport as a cause of de-
creased insulin-stimulated muscle glyco-
gen synthesis in type 2 diabetes. N Engl
J Med 341:240 –245, 1999
19. Begum N, Sussman KE, Draznin B: Differ-
ential effects of diabetes on adipocyte and
liver phosphotyrosine and phosphoserine
phosphatase activities. Diabetes 40:1620 –
1629, 1991
20. Nadiv O, Shinitzke M, Manu H, Hecht D,
Roberts CT, LeRoith D, Zick Y: Elevated
protein tyrosine phosphatase activity and
increased membrane viscosity are associ-
ated with impaired activation of the insu-
lin receptor kinase in old rats. Biochem J
298:443–450, 1994
21. Eldar-Finkelman H, Krebs EG: Phosphor-
ylation of insulin receptor substrate-1 by
glycogen synthase kinase 3 impairs insu-
lin action. Proc Natl Acad Sci 94:9660 –
9664, 1997
22. Dhuley JN: Antioxidant effects of cinna-
mon (Cinnamomum verum) bark and
greater cardamom (Amomum sabulatum)
seeds in rats fed high fat diet. Indian J Exp
Biol 37:238 –242, 1999
Cinnamon decreases glucose and lipids
3218 DIABETES CARE, VOLUME 26, NUMBER 12, DECEMBER 2003