Heart Health and Diabetes

What are the risk factors for type 2 diabetes?

Type 2 diabetes is by far the most common form of diabetes, accounting for 90–95% of all diabetics. Type 2 diabetics cannot use insulin efficiently and therefore cannot keep their blood sugar at normal levels.

For more information about type 2 diabetes, see “Type 2 Diabetes Quick Facts“. In this article, we discuss in more detail the factors that are associated with an increased risk of type 2 diabetes.

Obesity and fat distribution
People who are carrying excess body weight have a higher risk of type 2 diabetes. This is especially true if that extra fat is predominantly around in the abdomen (1). Obesity is classed as having a body mass index (BMI) of 30 or more, but even individuals with a BMI of 25–29.9 (overweight) are still at risk of type 2 diabetes. Calculate your BMI using this simple online calculator to see if you should lose a few pounds.

Family history of type 2 diabetes
A family history of type 2 diabetes is associated with an increased risk of disease, partly due to inherited genetic variants and also related to lifestyle influences (e.g., eating and exercise habits). There is no clear pattern of inheritance for type 2 diabetes because multiple different genetic variants all play a role (2).

High blood pressure
High blood pressure is linked to an increased risk of type 2 diabetes. Having type 2 diabetes is also linked to an increased risk of high blood pressure. The combination of both type 2 diabetes and high blood pressure significantly increases the risk of diabetic complications as well as cardiovascular health issues (3).

Altered lipid levels
Low levels of “good” HDL cholesterol and high levels of triglycerides are associated with an increased risk of type 2 diabetes. This increased risk occurs even when there are normal levels of “bad” LDL cholesterol (4).

Lack of physical activity
Physical activity is important for maintaining a healthy weight, using up extra glucose, and increasing cell responses to insulin. Therefore, those that are not getting enough exercise are at increased risk of type 2 diabetes, by not only increasing their risk of obesity but also influencing how their body responds to insulin (5).

Smoking
Smokers are 30–40% more likely to develop type 2 diabetes compared to non-smokers. High levels of nicotine can lessen the effects of insulin, meaning that smokers have to produce more insulin to get a proper response (6). Smoking is also associated with a higher likelihood of the serious health complications of diabetes, including heart disease, kidney disease, infections, ulcers, and eye problems (7).

Gestational diabetes
Gestational diabetes is a type of diabetes that develops during pregnancy, but blood sugar levels usually return to normal after delivery. However, about 50% of women with gestational diabetes go on to develop type 2 diabetes later in life. Gestational diabetes also increases the risk of the baby developing type 2 diabetes later in life too (8).

Prediabetes
A diagnosis of prediabetes means blood sugar (glucose) levels are above the normal range but are not considered high enough to be diabetes. However, prediabetes is taking a step in the wrong direction in regards to metabolic health. People with prediabetes have an increased risk of developing type 2 diabetes. The good news is, prediabetes can be reversed before developing any health complications associated with diabetes. See our previous article here for more information about prediabetes.

Race and ethnicity
People of certain races and ethnicities have an increased risk of type 2 diabetes, although the reasoning for this increased risk is still not fully understood. Races and ethnicities with an increased risk include African American, Alaska Native, American Indian, Asian American, Hispanic/Latino, Native Hawaiian, and Pacific Islander (1).

Age
Type 2 diabetes develops over many years, as the body struggles more and more to control the high level of glucose in the blood, combined with increasing insulin resistance as well as impaired pancreatic islet function with aging. The pancreatic islet cells are where insulin, the hormone that controls blood sugar, is produced. Therefore, increasing age is associated with an increased risk of type 2 diabetes, particularly after 45 years of age (9).

Polycystic ovary syndrome
Polycystic ovary syndrome (PCOS) is a common cause of female infertility. Affected women may have elevated androgen levels (hyperandrogenemia) and/or small cysts on one or both ovaries (polycystic ovaries) (10). Women with PCOS are often insulin resistant, meaning that their body is not effectively using insulin. This increases the risk of type 2 diabetes, with more than half of women with PCOS developing type 2 diabetes by 40 years of age (11). See our previous article here for more information about PCOS.

Depression
Depression is a risk factor for type 2 diabetes, with comparable importance to smoking and physical inactivity (12). Studies have also shown that more severe depression is associated with a higher risk of type 2 diabetes. In addition, type 2 diabetics have an increased risk of depression (13).

Areas of darkened skin
Areas of darkened skin, known as acanthosis nigricans, are a strong predictor for future diabetes. This is because excess insulin stimulates normal skin cells to reproduce at a rapid rate and these new skin cells contain more melanin so appear darker than the surrounding skin (14).

How is type 2 diabetes diagnosed?
Type 2 diabetes is diagnosed by measuring blood sugar (glucose) levels. The most effective method for this is with an HbA1c test, which is available here. HbA1c is glycated hemoglobin. It forms when hemoglobin within red blood cells joins with glucose. HbA1c levels reflect the average blood glucose level during the preceding 2-3 months. This differs from a blood glucose test, which measures the concentration of glucose at only the point at which the blood sample was collected.

  • Healthy HbA1c levels are less than 5.7%
  • 5.7% – 6.4% indicates prediabetes (increased risk of developing diabetes)
  • >6.5% supports a diabetes diagnosis

How can type 2 diabetes be prevented and treated?
Simple, proven lifestyle changes can help prevent or delay the onset of type 2 diabetes. These include losing excess body weight, eating healthier (especially reducing sugar and carbohydrate intake), and getting regular physical exercise. There are also different medication options available to help lower blood sugar levels. Read our previous article here for more tips to lower your blood sugar.

References:
1. Risk Factors for Type 2 Diabetes. (Reviewed Dec 2016). NIH, National Institute of Diabetes and Digestive and Kidney Diseases.
2. Ali O. (2013). Genetics of type 2 diabetes. World J Diabetes. 4(4): 114-123.
3. Golden SH, et al. (2003). Blood pressure in young adulthood and the risk of type 2 diabetes in middle age. Diabetes Care. 26(4): 1110–1115.
4. Krauss RM. (2004). Lipids and lipoproteins in patients with type 2 diabetes. Diabetes Care. 27(6): 1496–1504.
5. Venkatasamy VV, et al. (2013). Effect of physical activity on insulin resistance, inflammation and oxidative stress in diabetes mellitus. J Clin Diagn Res. 7(8): 1764–1766.
6. Cigarette smoking: A risk factor for type 2 diabetes. FDA.
7. Smoking and Diabetes. (Reviewed August 2021). CDC.
8. Gestational Diabetes. (Reviewed August 2021). CDC.
9. Kirkman MS, et al. (2012). Diabetes in older adults. Diabetes Care. 35(12): 2650–2664.
10. Ndefo UA et al. (2013) Polycystic Ovary Syndrome. Pharmacy and Therapeutics. 38(6): 348-355.
11. PCOS (Polycystic Ovary Syndrome) and Diabetes. (Reviewed March 2020). CDC.
12. Knol MJ et al. (2006) Depression as a risk factor for the onset of type 2 diabetes mellitus. A meta-analysis. Diabetologia. 49: 837–845.
13. Deleskog A, et al. (2019). Severity of depression, anxious distress and the risk of type 2 diabetes – a population-based cohort study in Sweden. BMC Public Health. 19, 1174.
14. Barwell J, Reviewed by Cobb C. (2019). Acanthosis Nigricans. Healthline.