Insulin in Type 2 diabetes may be harmful. This is why.
In Type 2 diabetic patients, diabetes is one of the manifestations of a seriously harmful disease process in the body called insulin resistance. Simply put, insulin resistance means your own insulin—a hormone naturally produced by the pancreas—becomes less effective in doing its job. In response to this insulin resistance, the pancreas produces more and more insulin. This large amount of insulin is not good for your body.
High Insulin in Type 2 Diabetes Causes High Blood Pressure
A high level of insulin in type 2 diabetes causes high blood pressure. This association between high insulin levels and the development of high blood pressure has been confirmed by several researchers (1).
High Insulin in Type 2 diabetes Causes Narrowing of the Blood Vessels
A high level of insulin in type 2 diabetes causes narrowing of the blood vessels, including coronary arteries. In this way, high insulin is associated with coronary artery disease. This association has been documented by several excellent clinical studies—The Helsinki Policeman Study (2), the Paris Prospective Study (3), and the Danish Study (4).
How does insulin cause heart disease? Insulin stimulates smooth muscle cell growth in the walls of the arteries. This leads to thickening and stiffness of arterial walls, which, in turn, contributes to narrowing of blood vessels (5).
Hypertension (high blood pressure) itself causes further narrowing of the blood vessels. Narrowed blood vessels lead to heart attacks and strokes.
High Insulin in Type 2 diabetes Causes Growth of Tumors, Including Cancer
A high level of insulin in type 2 diabetes also leads to the growth of tumors, benign as well as malignant. Why? Because insulin is a growth-promoting hormone. It causes growth of tissues – benign as well as cancerous. Several clinical studies have shown a high prevalence of cancer in people with Insulin Resistance Syndrome. Certain cancers, especially breast cancer, colon cancer and prostate cancer are linked to insulin resistance.
An excellent, large clinical study, known as the Nurses Health Study was published in 2003 in Diabetes Care (6). In this study, 111,488 American female nurses who were thirty to fifty-five years old and free of cancer in 1976 were followed through 1996 for the occurrence of Type 2 diabetes and through 1998 for breast cancer. Women with Type 2 diabetes were found to have a higher incidence of breast cancer than those who did not have diabetes.
Why Insulin in Type 2 Diabetes May be Harmful
Now imagine if a typical obese Type 2 diabetic patient, who is already producing a large amount of insulin as a result of insulin resistance, starts insulin to control the elevated blood sugars. Typically you need large doses of insulin -more than 40 units per day- to control blood sugars in obese type 2 diabetics. Giving large doses of insulin in type 2 diabetes is like adding fuel to the fire, isn’t it? That patient is already at high risk for heart disease, hypertension and cancer growth due to high insulin level. Adding more insulin in the form of insulin may control elevated blood sugar, but will increase the risk for high blood pressure, heart attack and cancer. The reverse is also true: If you treat Type 2 diabetes by treating its root cause, the insulin resistance, then you can reduce the risk of heart attack and cancer.
An excellent study from the University of Texas M.D. Anderson Cancer Center in Houston showed that patients with Type 2 diabetes who used insulin were 5 times more likely to develop pancreatic cancer compared to those who did not use insulin. On the other hand, patients who were on Metformin had a 62% lower risk for developing pancreatic cancer (7).
Metformin treats insulin resistance. Therefore, it was no surprise that Metformin caused a decrease in the risk for pancreatic cancer in this study.
Insulin also causes weight gain, retention of water and low blood sugar (hypoglycemia). Low blood sugar can be life-threatening. Perhaps now you can understand why the myopic approach to control blood sugar by insulin can be disastrous in many Type 2 diabetic patients.
An occasional thin patient with type 2 diabetes may need a small dose of insulin -less than 20 units per day. This small dose of insulin should not increase the risk of heart disease or cancer in these thin type 2 diabetics. However, even this small dose of insulin increases the risk of hypoglycemia.
You must never stop insulin or any other medication, without consulting your health care provider.
- Manicardi V, Camellini L, Bellodi G, Coscelli C, Ferrannini E. Evidence for an association between high blood pressure and hyperinsulinemia in obese men. J Clin Endocrinol Metabolism 1986; 62(6):1302–4.
- Pyorala K., Savolainen E, Kaukola S, Haapakoski J. Plasma insulin as coronary heart disease risk factor: relationship to other risk factors and predictive value during 9 1/2-year follow-up of the Helsinki Policemen Study. Acta Med Scand Suppl 1985; 701:38–52.
- Eschwege E, Richard JL, Thibult N, et al. Coronary heart disease mortality in relation with diabetes, blood glucose and plasma insulin level. The Paris Prospective Study, ten years later. Horm Metab Res Suppl 1985; 15:41–46.
- Moller LF, Jespersen J. Fasting serum insulin level and coronary heart disease in a Danish cohort: 17-year follow-up. J Cardiovasc Risk 1995; 2:235–240.
- Despres J-P, Lamarche B, et al. Hyperinsulinemia as an independent risk factor for ischemic heart disease. N Engl J Med 1996; 334:952–957. Salomaa V, Riley W, Kaark JD, et al. Non–insulin dependent diabetes mellitus and fasting insulin concentrations are associated with arterial stiffness index, the ARIC study. Circulation 1995; 91:1432–1443. 239
- Michels KB, Solomon CG, Hu FB, et al. Type 2 diabetes and subsequent incidence of breast cancer in the Nurses’ Health Study. Diabetes Care 2003; 26:1752–1758.
- Li D, Yeung SC, Hassan MM, Konopleva M, Abbruzzese JL. Antidiabetic therapies affect risk of pancreatic cancer. Gastroenterology. 2009 Aug;137(2):482-8