CARDIOVASCULAR JOURNAL OF AFRICA • Vol 21, No 1, January/February 2010
AFRICA
49
Insulin glargine and the risk of cancer
Dr FA Ahmed, Isipingo Hospital, Natal, reports on data presented at the 2009 EASD congress
The concerns about a possible link
between the use of Lantus (glargine)
insulin and an increased risk of cancer
were raised in the German study
1
of
around 127 000 insulin-treated patients
in an insurance database. The research
identified a statistically significant link
between patients who had used Lantus
insulin and those who had been diagnosed
with cancer.
Compared with people using similar
doses of human insulin, out of every 100
people who used Lantus insulin over an
average of about one-and-a-half years,
one additional person was diagnosed with
cancer. Of particular note in this study
was the finding that the increased risk of
cancer was dose dependent. Therefore for
patients given a dose of 10 units, Lantus
insulin alone increased the risk of cancer
by 9% compared with human insulin, but
for a dose of 50 units, the increased risk
was 31%.
Studies were then carried out using
databases from Sweden, Scotland and
the UK. The Swedish study
2
found that
compared with patients on insulins other
than Lantus insulin, patients on Lantus
alone had double the risk of breast cancer.
The Scottish study found a non-signifi-
cant increased risk for specifically breast
cancers.
3
The UK study found no link
between insulin glargine and cancer.
4
The researchers involved in all four
studies agreed that these finding were not
conclusive since the studies were obser-
vational and not clinical trials. The possi-
bility that differences between groups of
people were responsible for the differ-
ent rates of cancer cannot be excluded.
Further studies are needed before a final
conclusion can be reached.
Jay Skyler, MD of the University of
Miami, respresenting Sanofi-Aventis,
reviewed the four articles appearing in the
June 2000
Diabetologia
.
1–4
His conclu-
sion was that one of the studies support-
ed a special risk for insulin glargine
above that of other insulin drugs.
2
Skyler
also said that cancer incidences among
patients treated with insulin glargine in
uncontrolled analyses did not differ from
those reported in the CDC’s Surveillance,
Edpiemiolgy and End Results database
after adjusting for patient age.
Novo Nordisk proposed David Russel-
Jones, MD of the University of Surrey
in England, who reviewed clinical trial
data on insulin detemir compared with
two other insulin-based agents, including
glargine, covering some 9 000 patients.
He said that cancer incidence among
those receiving detemir was significantly
lower among patients treated with NPH
insulin. There was no significant differ-
ence in cancer rates between the detemir
and glargine analogues.
At a well-attended symposium at the
EASD, researchers reviewed the exist-
ing data on cancer and diabetes drugs,
including but not limited to insulin and
its analogues. What had emerged most
clearly, the researchers agreed, was that
patients receiving insulin-based agents,
and to a lesser extent sulfonylurea drugs,
appeared more likely to be diagnosed
with cancer.
Jeffrey Johnson, of the University of
Alberta in Edmonton, Canada, reviewed
data he and other scientists had reported
on earlier that year, covering patients in
Canada’s Saskatchewan province from
1995 to 2006. Compared with patients
receiving metformin monotherapy, those
taking sulfonylurea drugs were at a 30%
greater risk of being diagnosed with
cancer, Johnson said.
The data showed that patients receiving
insulin with fewer than 12 prescriptions
per year had a significant 67% increase
in the likelihood of cancer diagnosis,
relative to those on sulfonylurea mono-
therapy. Those receiving more insulin
prescriptions had a whopping sevenfold
increase in risk.
The researchers generally agreed on
several other points:
The retrospective data now availa-
●●
ble do not permit conclusions about
causality.
The current evidence suggesting insu-
●●
lin glargine-treated patients are at more
risk for cancer than patients receiving
other insulin-based agents is weak.
No association has been seen between
●●
metformin or thiazolidinediones and
increased cancer risks.
Some studies have suggested that
●●
metformin can reduce cancer risk, both
alone and in combination with insulin
glargine.
It is possible that insulins may promote
●●
cancer through their action as growth
factors.
It is also possible, however, that
●●
patients treated with insulin are at risk
for cancer because of the underlying
disease, not because of the drugs.
No associations were shown in young-
●●
er type 1 diabetics who most benefit
from insulin analogue therapy.
Conclusion
Prof UH Smith, president of the EASD
5
said that the associations between insulin
products and cancer risk fell far short
of demonstrating causality. They deserve
more research but do not warrant any
changes on treatment protocols at this
time, he said.
The EASD does not recommend that
patients should stop taking insulin glargine
on the basis of evidence presented in these
studies. Patients do however have the
option of using long-lasting human insu-
lin or a mixture of short- and long-acting
human insulin twice a day instead of the
once-daily analogue. Especially, patients
who already have cancer or women with a
family history of breast cancer may wish
to consider this option.
Hemkens LG,
1.
et al
. Risk of malignancies in
patients with diabetes treated with human
insulin or insulin analogues: a cohort study.
Diabetologia
2009;
52
(9):1732–1744. E-pub
30 June 2009.
Jonasson JM,
2.
et al
. Insulin glargine use and
short-term incidence of malignancies – a
population-based follow-up study in Sweden.
Diabetologia
2009;
52
(9): 1745–1754. E-pub
9 July 2009.
SDRN Epidemiology group. Use of insulin
3.
glargine and cancer incidence in Scotland:
A study from Scottish Diabetes research
network Epidemiology group.
Diabetologia
2009;
52
(9): 1755–1765. E-pub 15 July
2009.
Currie,
4.
et al
. The influence of glucose-
lowering therapies risk in type 2 diabe-
tes.
Diabetolgogia
2009;
52
(9): 1766–1777.
E-pub 2 July 2009.
Smith U, Gale EAM. Does diabetes therapy
5.
influence the risk of cancer?
Diabetologia
2009;
52
(9): 1699–1708.
