Daily usage of high insulin dose tied to cancer risk in type 1 diabetes: JAMA

Pennsylvania: There is a dose-dependent association between insulin and cancer incidence risk among type 1 diabetes (T1D) patients, states new study results published in the JAMA Oncology.

Diabetes and cancer are common diseases having a tremendous impact on health worldwide. Epidemiologic evidence suggests that people with diabetes are at significantly higher risk for many forms of cancer. In type 1 diabetes(T1D), the body cannot produce the hormone insulin, which helps regulate blood sugar levels. T1D patients are treated with insulin to survive. Insulin is known to increase cell production and reduces cell death, so there are chances that something may go wrong and cancer may develop. Previous studies have found a higher incidence of certain cancers in T1D compared with the general population. However, no studies have evaluated the risk factors of cancer incidence in T1D.

Zhong W, Merck Research Labs, Merck & Co Inc, Pennsylvania, and her team conducted a study to explore the associations of risk factors with cancer incidence in patients with T1D over a 28-year follow-up period.

Investigators used data from Diabetes Control and Complications Trial (DCCT) and the Epidemiology of Diabetes Interventions and Complications (EDIC) study and included 1303 patients who volunteered to continue in the EDIC follow-up study. Cancer incidence was calculated and associations of risk factors with cancer incidence were evaluated using Cox proportional hazards regression models. As daily insulin dose (time-dependent variable) remained significant in the multivariable model, it was also examined as a fixed variable (mean dose during follow-up). Investigators examined cancer incidence by 3 categories of mean daily insulin dose: low (<0.5 units/kg), medium (≥0.5 and <0.8 units/kg), and high (≥0.8 units/kg).

Key findings of the study,

• Of the total,7% had cancer diagnoses after a total of 33 813 person-years follow-up, and the incidence rate was 2.8 (95% CI, 2.2-3.3) per 1000 person-years.

• 9% developed cancer within 10 years, 33% developed cancer between 11 and 20 years, and 58% developed cancer between 21 and 28 years.

• Age and sex were associated with cancer incidence, for age (HR-1.08 ); for female sex(HR-1.74)

• Exercising habits and high-density lipoprotein cholesterol were inversely associated and daily insulin dose was associated with cancer incidence after adjusting for age and sex.

• Daily insulin dose remained associated with cancer incidence in the multivariable model 1 (HR-5.93) and model 2 (HR-4.13)

• Cancer incidence was 2.11, 2.87, and 2.91 per 1000 person-years in the low-, medium-, and high-dose groups, respectively.

The authors conclude that daily insulin dose is associated with cancer risk in T1D. The study showed that the HRs were significantly higher in the high-dose vs low-dose group, suggesting those using higher daily doses of insulin had a more than 4-fold increase in the risk of a cancer diagnosis. In the future, larger studies in T1D are needed to validate this association.

Reference:

Zhong W, Mao Y. Daily Insulin Dose and Cancer Risk Among Patients With Type 1 Diabetes. JAMA Oncol. Published online July 28, 2022. doi:10.1001/jamaoncol.2022.2960