Nutritional Supplements That Lower Glucose
When considering nutritional supplements to lower
glucose levels, one need to keep a number of issues in mind:
There is limited information supporting the glucose-lowering effect of many supplements. Sometimes there are
just a few anecdotal reports rather than carefully performed scientiﬁc studies. What scientiﬁc studies there
are, on closer inspection, have major ﬂaws. The reason there are no large clinical studies for supplements is
that these studies are very expensive to do. In some cases, the evidence that a particular chemical may have a
role in glucose control is based on experiments in animals with a severe deﬁciency of the chemical. But this
type of deﬁciency may occur only infrequently in humans. For example, chromium deﬁciency in rats causes insulin
resistance, but it is difﬁcult to show that degree of deﬁciency in humans consuming a normal diet, and so the
relevance to human diabetes is unclear.
• Since nutritional supplements are not regulated in the same manner as
pharmaceutical medicines, supplements may vary in terms of potency.
• Just because a compound is not regulated and is natural does not make it
safe—there could be serious side effects, and the supplement could also affect the metabolism of other drugs
that are taken at the same time.
Here some of the more popular supplements.
In a laboratory cell culture, extracts of cinnamon have been shown to
enhance the action of insulin. In 2003, the journal Diabetes
Care published a study that reported that cinnamon extract lowered
fasting glucose, triglycerides, and LDL cholesterol in thirty patients with type 2 diabetes. This study got a
lot of attention in the media, and many people with diabetes wonder if cinnamon would help their diabetes.
However, a smaller study published in The Journal of
Nutrition in 2006 with twelve subjects taking cinnamon extract did
not show any beneﬁt. In both studies the patients were also on other diabetes medicine. In the 2003 study they
were all on sulfonylureas, whereas in the 2006 study they were on sulfonylureas with or without metformin or
metformin or thiazolidinediones with or without metformin or a reduced-calorie diet. It is possible that this
difference may explain the lack of response in the second study.
When rats are given a diet deﬁcient in chromium, they have higher glucose
levels. Similarly, humans who are on intravenous nutrition (total parenteral nutrition), if they are not given
chromium supplements, have higher glucose levels and insulin resistance. It has not been shown that people with
diabetes have chromium deﬁ ciency, but when chromium picolinate has been given to people with diabetes, a
number of studies have shown a beneﬁt. For example, in a study published in the journal
Diabetes Care in 2006,
seventeen patients with type 2 diabetes on sulfonylureas who were given 1,000 micrograms of chromium had an
improvement in glucose control and insulin sensitivity. This dose is much higher than the recommended daily
dose, which is 20 to 35 micrograms daily. It appears to be fairly safe at the high dose, although there have
been two cases of kidney problems and one case of liver damage reported. A longer-duration study with a
larger number of subjects is needed to ﬁnd out if chromium supplements are beneﬁcial for people with
diabetes. An important question is whether the supplement adds much for patients who already may be on
several drugs for their diabetes.
The trace element selenium is important in the activity of a number
proteins in the body—these are known as selenoproteins. Glutathione peroxidases and cellular antioxidants are
selenoproteins, and so selenium’s antioxidant properties have been a focus of clinical studies. So far, however,
there are no studies showing that selenium supplementation is beneﬁcial in people with
Several small studies reported an improvement in fasting glucose and HbA1c
with 3 grams of American ginseng. The studies are of limited duration (eight weeks). Reported side effects of
American ginseng include insomnia, high blood pressure, and anxiety.