High Blood Sugar and Insulin Resistance

Repeated high blood sugar levels can create imbalances leading to insulin resistance. Chronically high levels of blood sugar and insulin can create conditions favorable to cancer growth and spread.

Why are high blood sugar and insulin resistance important?

High blood sugar and/or insulin resistance can affect cancer risk and outcomes, plus other body terrainthe internal conditions of your body, including nutritional status, fitness, blood sugar balance, hormone balance, inflammation, and more factors connected to cancer. 

Direct connections to cancer 

Chronically high blood sugar may accelerate cancer progression, invasion, and migration to other areas of the body. High blood sugar may also help cancer cells resist normal cell death and may promote resistance to chemotherapy. It prompts the body to produce substances that promote inflammation and may be linked to development of tumors.1Li W, Zhang X et al. Effects of hyperglycemia on the progression of tumor diseases. Journal of Experimental & Clinical Cancer Research. 2019 Jul 23;38(1):327. 

“Insulin increases cell production and reduces cell death”2Underferth D. Sugar, insulin resistance and cancer: What’s the link? MD Anderson Cancer Center. June 21, 2021. Viewed August 12, 2022.—two hallmarks of cancer. Relatively small but chronic rises in blood sugar or insulin may contribute to cancer growth.3Mulholland HG, Murray LJ, Cardwell CR, Cantwell MM. Dietary glycaemic index, glycaemic load and endometrial and ovarian cancer risk: a systematic review and meta-analysis. British Journal of Cancer. 2008 Aug 5;99(3):434-41. Chronic high levels of insulin are linked to diabetes and several types of cancer.4Yin M, Zhou J, Gorak EJ, Quddus F. Metformin is associated with survival benefit in cancer patients with concurrent type 2 diabetes: a systematic review and meta-analysis. Oncologist. 2013 Dec;18(12):1248-1255; Underferth D. Sugar, insulin resistance and cancer: What’s the link? MD Anderson Cancer Center. June 21, 2021. Viewed August 12, 2022.

Managing high blood sugar and insulin resistance is very important for reducing your risk of poor cancer outcomes. A combination of self-care practices including Eating Well and Moving More, medication use as directed by your physician, and use of appropriate complementary therapies, all carefully monitored by your physician, can improve your levels and reduce your risk of poor cancer outcomes. See What approaches can help you manage high blood sugar and insulin resistance? ›

Largely due to increased blood sugar and insulin resistance, people with diabetes are at higher risk of poor cancer outcomes compared with nondiabetic people with cancer, as shown in these charts.

A graph shows increased mortality among people with cancer who also have diabetes.

*Cancer-specific survival; all others are overall survival

A graph shows increased risk of some types of cancer among people who have diabetes.

Note: Studies, detailed below, reported different mortality time points, from one year to more than eight years. Some studies reported mortality among more specific populations, such as people at a specific cancer stage or with a specific subtype of cancer. When more than one study reported differing numbers on mortality, we used the more conservative numbers.

Cancer as a whole

Good evidencesignificant effects in one large or several mid-sized and well-designed clinical studies (randomized controlled trials (RCTs) with an appropriate placebo or other strong comparison control or observational studies that control for confounds) (this is the CancerChoices definition; other researchers and studies may define this differently) of moderately higher mortality among people with cancer with pre-existing diabetes

Good evidence of slightly higher mortality among people with solid tumors with diabetes

Modest evidencesignificant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observational studies), or several small studies aggregated into a meta-analysis (this is the CancerChoices definition; other researchers and studies may define this differently) of higher risk of cancer as a whole, including invasive cancer, among people with diabetes

Good evidence of higher cancer-specific mortality among people without cancer at baseline with poorer markers of blood sugar balance and insulin sensitivity

Bladder cancer

Preliminary evidencesignificant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect (this is the CancerChoices definition; other researchers and studies may define this differently) of higher rate of cancer progression among people with non-muscle invasive bladder cancer with diabetes with high blood sugar levels

Good evidence of moderately higher risk of cancer recurrence among people with bladder cancer with diabetes

Brain cancer

Modest evidence of lower overall survival among people with glioblastoma and with high blood sugar levels

Breast cancer

Modest evidence of worse survival among people with breast cancer with diabetes

Modest evidence of higher risk of breast cancer among women with diabetes, including gestational diabetes

Colorectal cancer

Modest evidence of higher mortality among people with colorectal cancer with the highest insulin index or insulin load

Preliminary evidence of higher local tumor malignancy among people with colorectal cancer with higher blood glucose levels

Good evidence of higher risk of colorectal cancer among people with type 2 diabetes

Modest evidence of higher risk of colorectal cancer among people with diabetes

Preliminary evidence of substantially higher risk of recurrence among people with stage 3 colorectal cancer with high blood glucose

Gastrointestinal cancer

Good evidence of higher risk of gallbladder cancer among people with type 2 diabetes

Preliminary evidence of substantially worse survival after radiofrequency ablation among people with early hepatocellular carcinoma (HCC) with diabetes

Preliminary evidence of higher risk of recurrence of hepatocellular carcinoma after initial liver resection among people with diabetes and with HbA1c higher than 9%

Good evidence of higher risk of hepatocellular carcinoma among people with type 2 diabetes

Gynecologic cancer

Good evidence of a link between type 2 diabetes or insulin resistancea condition in which cells in your muscles, fat, and liver don’t respond well to insulin and can’t efficiently take up glucose from your blood for energy and endometrial cancer

Modest evidence of higher risk of developing cancer in any organ with high levels of estrogen receptors—including breast, endometrium, and ovaries—among people with decreased levels of estrogen as a result of insulin resistance

Head and neck cancers

Modest evidence of substantially higher cancer-specific mortality among people with head and neck cancer and diabetes

Kidney cancer

Modest evidence of a link between insulin resistance and renal cell carcinoma

Good evidence of higher risk of kidney cancer among people with diabetes

Lung cancer

Insufficient (conflicting) evidence of an effect on mortality among people with lung cancer with diabetes

Weak evidence of higher risk of lung cancer among people with diabetes, with stronger effects among women

Preliminary evidence of higher risk of lung cancer among people with higher insulin levels and resistance

Lymphoma

Weak evidenceone or more case studies, supported by animal evidence OR small treatment effects of limited clinical significance OR studies with no controls OR weak trends of effects (this is the CancerChoices definition; other researchers and studies may define this differently) of higher overall and lymphoma-specific mortality among people with diabetes

Ovarian cancer

Preliminary evidence of shorter median progression-free and overall survival among people with ovarian cancer and diabetes

Modest evidence of higher risk of ovarian cancer among people with diabetes

Modest evidence of higher risk of developing cancer in any organ with high levels of estrogen receptors, including ovaries, among people with decreased levels of estrogen as a result of insulin resistance

Pancreatic cancer

Modest evidence of worse survival of pancreatic cancer among people with diabetes

Good evidence of higher risk of pancreatic cancer among people with diabetes

Prostate cancer

Modest evidence of higher mortality among people with prostate cancer with diabetes

Modest evidence of a link between higher fasting insulin levels, insulin resistance and prostate cancer

Thyroid cancer

No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. of diabetes or prediabetes on cancer outcomes among people with differentiated thyroid cancer

Good evidence of a substantially higher risk of thyroid cancer among people with insulin resistance

Connections to body terrain factors

Hyperglycemia and insulin resistancea condition in which cells in your muscles, fat, and liver don’t respond well to insulin and can’t efficiently take up glucose from your blood for energy have links to all the other body terrainthe internal conditions of your body, including nutritional status, fitness, blood sugar balance, hormone balance, inflammation and more factors. Sometimes the cause and effect are seen in both directions (bidirectional). Sometimes an imbalance in one terrain factor causes a domino effect, toppling the balance of other terrain factors. Details of these connections follow, but first we want to emphasize the web of connections among factors that aren’t as apparent by looking at factors one at a time.

For instance, hyperglycemia and insulin resistance trigger a cascade of immune events that promote inflammation, which, along with oxidative stressan imbalance between free radicals and antioxidants in your body in which antioxidant levels are lower than normal; this imbalance can cause harmful oxidation reactions in your body chemistry can then damage the inside of blood vessels and lead to coagulation problems such as developing blood clots along the lining of these vessels. While the “fires of inflammation” are burning, other immune functions, such as protection against infection, may be hampered by uncontrolled hyperglycemia and insulin resistance. People with diabetes are at higher risk for infection. 

Obesity (high body weight) is linked to insulin resistance, often being cited as the cause, but more recently being proposed as a possible result of insulin resistance. The relationship is complex, and measures to control weight and reduce insulin resistance are important pieces in optimizing your terrain.66Diabesity: How Obesity Is Related to Diabetes. Cleveland Clinic. November 8, 2021. Viewed September 15, 2022.

Another two-way link is between hyperglycemia/insulin resistance and hormone imbalances. Diabetes itself is a hormone imbalance condition,67Are Diabetes and Hormonal Imbalances Linked? Matthews Internal Medicine. Viewed September 15, 2022. but other hormones besides insulin can be involved. For instance, low testosterone is common in men with diabetes and is linked to insulin resistance. Estrogen may increase insulin sensitivity, while progesterone may reduce that sensitivity.

When a person is under stress, the body increases its release of stress hormones (glucocorticoids) such as cortisol and epinephrine. These hormones can impair the effects of insulin and slow down glucose absorption,68Bauerle KT, Harris C. Glucocorticoids and diabetes. Missouri Medicine. 2016 Sep-Oct;113(5):378-383. ensuring enough glucose is in the blood to provide energy for the fight-or-flight response. If stress hormones remain high for a prolonged time, chronically high levels of glucose in the blood can develop. 

Stress hormones surge during acute stress, but are also released in a daily up and down rhythm based on the body’s internal clock. For instance, stress hormones are normally lower during sleep and rise after waking. If these daily (circadian) rhythms are disrupted, such as from inadequate sleep or reversed sleep-wake times, hormones that affect glucose control, insulin resistance and basic metabolism can also get out of rhythm. In people with diabetes, these hormonal release rhythms may be disrupted, dangerously affecting blood sugar levels in the early morning. 

Not only do stress hormones follow a daily rhythmic pattern, but other hormones as well, including hormones related to metabolism. “An intimate relationship between circadian clocks and endocrine systems exists. This relationship is clinically relevant since disruption of the circadian clock is linked to metabolic disease.”69Pillon NJ, Loos RJF, Marshall SM, Zierath JR. Metabolic consequences of obesity and type 2 diabetes: Balancing genes and environment for personalized care. Cell. 2021 Mar 18;184(6):1530-1544. Metabolic hormones such as leptin, insulin and others respond to fasting/feeding cycles. Eating late at night, when the body is normally expected to fast, is linked to overweight and poor glycemic control. 

Your microbiomethe collection of microbes living on and within your body also influences and is influenced by glucose. Because of its important metabolic function, your microbiome may influence the development of both obesity and diabetes. An imbalanced gut microbiota is linked to impaired glycemic control and development of type 2 diabetes in the host.70Gérard C, Vidal H. Impact of gut microbiota on host glycemic control. Frontiers in Endocrinology (Lausanne). 2019 Jan 30;10:29.

Measures to improve the health of your microbiome, such as through a diet including foods that are fermented or high in fiber, may promote beneficial microorganisms and contribute to the health of your metabolism. Healthy fermented foods include yogurt, miso, tempeh, and fermented vegetables such as sauerkraut.

Bottom line: Insulin resistance and high blood glucose affect and/or are affected by all the other terrain factors. We recommend you work with your healthcare practitioner to determine which terrain imbalances you may have and what is driving those imbalances. Then you can make a plan to optimize your terrain in the most sensible way. For instance, if you have high blood sugar and insulin resistance as well as chronic sleep disruption, it may make sense not only to treat your blood sugar and insulin balance up front, but also to improve your sleep.

Find health professionals who specialize in managing body terrain ›

Bleeding and coagulation imbalance

Many cancer types increase risk of coagulation problems. Some types of cancer increase risk of blood clots, while others increase risk of bleeding. If you’re at higher risk of blood clots, diabetes could increase your risk further.

Preliminary evidencesignificant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect (this is the CancerChoices definition; other researchers and studies may define this differently) of increased blood clotting and platelet activation among people with type 2 diabetes and cardiovascular disease

Body weight

Modest evidencesignificant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observational studies), or several small studies aggregated into a meta-analysis (this is the CancerChoices definition; other researchers and studies may define this differently) of excessive fat accumulation among people after developing insulin resistance

Modest evidence of better blood sugar and insulin sensitivity among people losing weight

Preliminary evidence of more weight loss among obese people who reduced high blood sugar levels

Hormone imbalance

Links between changes in metabolic hormones such as glucagon and diabetes

Preliminary evidence of high rates of testosterone deficiency among men with type 2 diabetes

Preliminary evidence of a link between low testosterone levels and insulin resistance among men with either type 1 diabetes or type 2 diabetes

Immune function

Modest evidence of impaired immune function among people with diabetes or high blood sugar

Inflammation

Good evidencesignificant effects in one large or several mid-sized and well-designed clinical studies (randomized controlled trials (RCTs) with an appropriate placebo or other strong comparison control or observational studies that control for confounds) (this is the CancerChoices definition; other researchers and studies may define this differently) of higher inflammation among people with type 2 diabetes

Oxidative stress

Modest evidence of higher incidence of oxidative stress among people with type 2 diabetes

Your microbiome

Modest evidence of a bidirectional link between insulin sensitivity/diabetes and gut microbial composition and diversity

Connections to symptoms and side effects

Symptoms not specific to cancer

Modest evidencesignificant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observational studies), or several small studies aggregated into a meta-analysis (this is the CancerChoices definition; other researchers and studies may define this differently) of higher levels of vascular injury and risk of cardiovascular disease, heart attack (myocardial infarction), stroke, and peripheral artery disease among people with type 2 diabetes

Modest evidence of higher risk of cognitive dysfunction among people with diabetes or increased insulin resistance

Good evidencesignificant effects in one large or several mid-sized and well-designed clinical studies (randomized controlled trials (RCTs) with an appropriate placebo or other strong comparison control or observational studies that control for confounds) (this is the CancerChoices definition; other researchers and studies may define this differently) of higher incidence of depression among people with higher levels of blood sugar or type 2 diabetes

Preliminary evidencesignificant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect (this is the CancerChoices definition; other researchers and studies may define this differently) of a link between depression and high blood sugar, but no evidence specific to people with cancer

Modest evidence of slower progression of neuropathy among some people with type 2 diabetes or delay of the development of neuropathy among patients with type 1 diabetes practicing tight glycemic control

Modest evidence of a link between insulin resistance and pain

Modest evidence of higher risk of infection and other complications, including short-term mortality, after surgery among people with poor glycemic control and/or insulin resistance

Modest evidence of longer hospital and/or intensive care unit (ICU) stays after surgery among people with diabetes with poor glycemic control

Helpful links

Authors

Laura Pole, MSN, RN, OCNS

Senior Clinical Consultant
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Laura Pole is senior clinical consultant for CancerChoices. Laura is an oncology clinical nurse specialist who has been providing integrative oncology clinical care, navigation, consultation, and education services for over 40 years. She is the co-creator and co-coordinator of the Integrative Oncology Navigation Training at Smith Center for Healing and the Arts in Washington, DC. Laura also manages the “Media Watch Cancer News That You Can Use” listserv for Smith Center/Commonweal. In her role as a palliative care educator and consultant, Laura has served as statewide Respecting Choices Faculty for the Virginia POST (Physician Orders for Scope of Treatment) Collaborative as well as provided statewide professional education on palliative and end-of-life care for the Virginia Association for Hospices and Palliative Care.

For CancerChoices, Laura curates content and research, networks with clinical and organizational partners, brings awareness and education of integrative oncology at professional and patient conferences and programs, and translates research into information relevant to the patient experience as well as clinical practice.

Laura sees her work with CancerChoices as a perfect alignment of all her passions, knowledge and skills in integrative oncology care. She is honored to serve you.

Laura Pole, MSN, RN, OCNS Senior Clinical Consultant

Nancy Hepp, MS

Lead Researcher
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Ms. Hepp is a researcher and communicator who has been writing and editing educational content on varied health topics for more than 20 years. She serves as lead researcher and writer for CancerChoices and also served as the first program manager. Her graduate work in research and cognitive psychology, her master’s degree in instructional design, and her certificate in web design have all guided her in writing and presenting information for a wide variety of audiences and uses. Nancy’s service as faculty development coordinator in the Department of Family Medicine at Wright State University also provided experience in medical research, plus insights into medical education and medical care from the professional’s perspective.

Nancy Hepp, MS Lead Researcher

Reviewer

Dr. Fuller-Shavel is a GMC-registered integrative medicine doctor with degrees in medicine and natural sciences from the University of Cambridge. Dr. Fuller-Shavel is a fellow of the College of Medicine and the vice chair for BSIO (British Society for Integrative Oncology). Alongside her science and medical training, Dr. Fuller-Shavel holds multiple qualifications in nutrition, integrative medicine, health coaching, herbal medicine, yoga, mindfulness and other mind-body approaches.

Dr. Fuller-Shavel is the director of Synthesis Clinic, an award-winning multidisciplinary integrative medicine practice in Hampshire, UK, specializing in women’s health, gut health (microbiome and gut-brain axis) and mental health. She combines her clinical work in women’s health and supporting patients with breast and gynecological cancer with education and training for healthcare professionals and research in precision cancer medicine and precision nutrition.

Nina Fuller-Shavel, MB, BChir, MA Hons, FBANT, IFMCP, DipIM, PG Cert RYT300

Last update: May 10, 2024

Last full literature review: July 2022

CancerChoices provides information about integrative in cancer care, a patient-centered approach combining the best of conventional care, self care and evidence-informed complementary care in an integrated plan cancer care. We review complementaryin cancer care, complementary care involves the use of therapies intended to enhance or add to standard conventional treatments; examples include supplements, mind-body approaches such as yoga or psychosocial therapy, and acupuncture therapies and self-care lifestyle actions and behaviors that may impact cancer outcomes; examples include eating health-promoting foods, limiting alcohol, increasing physical activity, and managing stress practices to help patients and professionals explore and integrate the best combination of conventionalthe cancer care offered by conventionally trained physicians and most hospitals; examples are chemotherapy, surgery, and radiotherapy and complementary therapies and practices for each person.

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