Does daily dose of insulin increase risk of cancer in patients with type 1 diabetes?

Type 1 diabetes mellitus is a chronic medical condition that occurs when the pancreas, an organ in the abdomen, produces very little or no insulin. Due to this, patients with type 1 diabetes require daily doses of insulin — which can be adminered under the skin, either as a shot or with an insulin pump — to meet the body’s requirements. The dosage is monitored minutely and adjusted to the body’s needs over time.
While a necessity for diabetics, a JAMA study noted that a daily dose of human insulin, which is usually injected subcutaneously several times a day, may increase cancer risk in type 1 diabetes patients. The study, using data from the Diabetes Control and Complications Trial (DCCT) and the Epidemiology of Diabetes Interventions and Complications (EDIC) studies, explored the associations of risk factors with cancer incidence in patients with type 1 diabetes over a 28-year follow-up period.

With a sample size of 1,303 patients, the study showed that hazard ratios were significantly higher in the high-dose vs low-dose group. It further analysed 50 common risk factors like smoking, alcohol, medication, and family hory.
It noted that of the 1,303 patients in the cohort, 93 (7 per cent) had cancer diagnoses, and the incidence rate was 2.8 (95 per cent) per 1,000 person-years. At first diagnosis, the mean age was 50 years, and the mean duration of diabetes was 25 years. Among 93 patients, 57 were female individuals (61 per cent), 36 were male individuals (39 per cent), 8 (9 per cent) developed cancer within 10 years, 31 (33 per cent) developed cancer between 11 and 20 years, and 54 (58 per cent) developed cancer between 21 and 28 years.
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But what is the connection?
Diabetes and cancer are chronic conditions, and the burden of these two is “increasing at an alarming rate in the country”, said Dr Aniket Mule, consultant internal medicine, Wockhardt Hospitals Mira Road.

“Obesity can be a driving factor behind diabetes and cancer which, in turn, leads to higher mortality and morbidity rates around the world. As per the evidence available, diabetes is a significant marker of altered cancer risk due to various changes in metabolic conditions like insulin resance or hyperinsulinemia. In the study, those who took higher doses of insulin had a risk of a cancer diagnosis,” Dr Mule said. However, it is too early to directly link insulin, which is a “life-saving drug” to cancer, experts said.
“While there is always a chance that exogenously given insulin can promote growth factors which can cause the proliferation of certain cells, in diabetes management, there are many therapeutic modalities, out of which insulin is a life-saving method almost equivalent to Sanjeevani booti (medicinal herb Selaginella bryopteris known to cure any malady),” Dr Anil Bhoraskar, senior diabetolog, SL Raheja Hospital, Mahim, and secretary, Diabetic Association of India (Scientific Section) told .
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Stressing that cancer cases have been on the rise, Dr Bhoraskar pointed out that “many factors” could be responsible for the same. “These include nutrition deficiency, air and water pollution, along with food pollution caused due to use of chemicals and fertilisers. All these factors could be responsible for inducing oxidative stress leading to free-radical formation,” he said.
There is a lot of mixed data out there, rued Dr Tanvi Sood, Consultant- Medical Oncology, Paras Hospitals Gurugram. “Maybe the patient has other risk factors like diabetes, and obesity already exing in the body, which causes a higher risk of cancer formation, but the usage of regular insulin for getting down the blood sugar levels and having a good control on diabetes, does not pose any additional threat of cancer formation,” she told .
What must be done?
“It is imperative for one to avoid getting stressed and anxious, and adhere to a well-balanced lifestyle inclusive of healthy eating, exercising daily, staying stress-free, and maintaining an optimum weight to keep cancer at bay and manage blood sugar levels,” Dr Mule said.
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