The Connection Between Cancer and Diabetes

By Wendy Kaplan, MS, RDN, CSO, CDCES, CDN

There is growing evidence of a significant link between cancer and diabetes. It is increasingly common for both diseases to be diagnosed within the same patient, as they share overlapping risk factors and etiological pathways. Diabetes increases the risk of developing cancer, and cancer, in turn, increases the risk of developing diabetes.

Specifically, individuals with type 1 diabetes have an increased risk of stomach, liver, kidney, pancreatic, and endometrial cancers, while their risk of breast and prostate cancers is decreased. For those with prediabetes and type 2 diabetes, the risk of liver, pancreas, and endometrial cancers is twice as high, and the risk of colorectal, breast, and bladder cancers is 1.2-1.5 times higher. However, the risk of prostate cancer is lower.

Despite its significance, the link between cancer and diabetes remains an under-discussed topic in clinical practice. Studies have even suggested that just a few days of hyperglycemia can harm the immune system. Having diabetes prior to a cancer diagnosis further complicates cancer treatment, and certain cancer treatments themselves can induce diabetes. It is worth noting that in cases of treatment-induced diabetes (or steroid diabetes), not all patients were predisposed to the disease.

We commend NYCBS for its leadership in cancer care and efforts to address this critical area. My fellow RDN colleagues and I have diligently pursued the CDCES (Certified Diabetes Care and Education Specialist) board certification to better serve our patients and multidisciplinary teams.

Fortunately, advances in cancer treatments have resulted in increased cancer survivorship. However, with higher rates of survivorship come additional health concerns, such as prediabetes and diabetes. Cancer survivors are at risk of experiencing multiple long-term and late-term side effects, some of which may begin during treatment.

One of the key elements in managing the link between cancer and diabetes is understanding the negative effects of certain treatments on diabetes and other endocrine issues. Treatments such as antineoplastic agents, glucocorticoids, hormone-based therapies, and radiation have been associated with detrimental effects on the development and management of diabetes. The possible mechanisms for this direct link include hyperinsulinemia, hyperglycemia, and inflammation.

Hyperinsulinemia occurs when the body produces excessive amounts of insulin to compensate for elevated blood glucose levels. Chemotherapy and other cancer treatments can suppress immune function, which, when combined with hyperglycemia, further compromises the immune system and increases the risk of infections, such as bacterial and fungal infections. Additionally, factors such as inactivity, emotional stress, and excess weight (overweight or obesity) contribute significantly to hyperglycemia. Excess weight can lead to increased insulin levels, higher glucose levels, and potentially support tumor growth.

As with many other diseases and chronic conditions, there are modifiable and non-modifiable risk factors associated with cancer and diabetes. While we cannot control factors such as age and ethnicity, we can make proactive choices regarding our diet, weight management, physical activity levels, alcohol consumption, and smoking habits to prevent or slow down the progression of these conditions.

As Registered Dietitian Nutritionists (RDNs), we collaborate with our patients to develop realistic and achievable goals for healthy eating and lifestyle changes. Our aim is to improve clinical parameters, enhance overall health, and optimize body composition by promoting the increase of lean mass and reducing fat mass.

Addressing the link between cancer and diabetes requires a comprehensive approach that combines medical intervention, dietary modifications, and lifestyle changes. It is crucial to work closely with healthcare professionals, including RDNs, to develop an individualized plan that supports optimal health and well-being.

Sometimes, patients undergoing cancer treatment and post-treatment experience weight gain. This weight gain tends to be in the form of central adiposity, or fat mass, rather than lean body mass. Unfortunately, cancer and its treatment can cause several metabolic changes, including hormone level decreases that lead to insulin resistance, as well as increased estrogen levels and other factors that contribute to this weight gain.

Another factor to consider is that cancer patients may not feel well during treatment, resulting in suboptimal oral intake. In such cases, the "ideal healthy eating pattern" may need to be adjusted to a more liberalized diet that meets the patient's protein and energy needs and accommodates their taste preferences. Since patients are at different stages of disease during treatment, they may experience varying nutritional impact symptoms and side effects, which can affect food cravings, energy levels, and overall mood.

Medical nutrition therapy (MNT) is an essential intervention to address this concern, and it may include the following strategies:

- Promoting healthy food choices and patterns, such as plant-based, Mediterranean, or DASH diets.

- Limiting refined carbohydrates in the diet.

- Adjusting calorie, sugar, and fat intake to meet individual needs.

- Determining healthy macronutrient ratios to manage blood sugar.

- Promoting meal consistency by consuming meals and snacks at regular times each day.

- Pairing protein with carbohydrate foods to stabilize blood sugar levels.

- Educating on healthy portion sizes and appropriate portion control.

- Encouraging physical activity and discouraging sedentary behavior.

- Encouraging short brisk walks after meals to aid digestion and insulin sensitivity.

- Increasing fiber intake through whole grains, legumes, fruits, and vegetables.

- Decreasing red meat consumption and exploring alternative protein sources.

- Urging smoking cessation, as smoking has negative effects on overall health.

While some of these recommendations may seem general, registered dietitian nutritionists (RDNs) help establish specific goals tailored to an individual's unique needs, considering their medical conditions, comorbidities, cultural preferences, and more. The goal is to support patients in implementing these strategies effectively.


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