Smoking and Diabetes Risk: A Deadly Combination

It comes as no surprise to anyone reading this blog that smoking is bad for your health. Interestingly, the risk goes far beyond cancer risk and heart disease - smoking has an important impact on diabetes as well.

As reviewed by Patasi and Hall, several studies have demonstrated that smoking increases the risk of developing type 2 diabetes 2- to 3- fold. The likely reason behind this fact is that smoking decreases the body's ability to use insulin. In fact, smoking 1 cigarette reduces the body's ability to use insulin by 15% for an entire day! We also see that amongst patients with type 2 diabetes, smokers have higher blood sugars than nonsmokers.

Vascular disease is a complication of both smoking and diabetes, so it should come as no surprise that having both risk factors compounds the risk. Smoking diabetes are more than 10 times more likely to develop peripheral vascular disease than nonsmoking diabetics, and also have a higher risk of small vessel diabetic complications such as nerve, eye, and kidney damage. Smoking can also lead to impotence amongst diabetic men. And that's not all - the list goes on.

Given that we know that smoking increases the risk of several cancers as well as the risk of vascular disease, and that 80% of diabetics will die as a result of heart disease or stroke, smoking and diabetes are truly a deadly combination.

Dr Sue Pedersen www.drsue.ca © 2011 drsuetalks@gmail.com

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Are Genetics Important in Diabetes?

In a world where the epidemic of diabetes threatens to spiral out of control, our understanding of the influences that put people at risk of developing the disease is crucial.  As a second part to my recent blog about the important genetic influence on the development of obesity, it is also very important to consider the genetic contribution towards diabetes.

In North America, approximately 80% of diabetes is caused by Type 2 Diabetes, which is a condition of elevated blood sugars caused by resistance of the body's organs and tissues to the effects of insulin, to the point where the pancreas is not able to produce sufficient insulin to overcome this state of insulin resistance.  Insulin resistance and Type 2 Diabetes worsen with weight gain and improve with weight loss; however, there are a subset of people with Type 2 Diabetes who are normal weight.   About 10% of diabetes is Type 1 diabetes, where the immune system attacks the pancreas and causes it to fail to produce insulin.  The final 10% of diabetes is causes by various rare genetic disorders.

The evidence for a strong genetic tendency towards developing Type 2 Diabetes is strong.  For example:

• some ethnic groups residing in North America (such as Hispanic, South Asian, and Aboriginal) are at 2-6 fold higher risk of developing Type 2 Diabetes compared to North American Caucasians
• a twin of a person with Type 2 Diabetes is at 90% risk of developing the disease (as compared to Type 1 diabetes, where the risk is lower at 50%)
• nearly 40% of patients with Type 2 Diabetes have at least one affected parent (whereas in Type 1 Diabetes, the risk of the child of a Type 1 Diabetic parent getting the disease is only 6%)
• the lifetime risk of a person getting Type 2 Diabetes is 5-10 times higher if they have a first degree relative with the disease, compared to not having a relative with the disease

As reviewed by Dr McCarthy, the search for genes connected to Type 2 Diabetes has really taken off with the ability to search the entire human genetic makeup (called the 'genome') in recent years.  In fact, there are at least 40 genetic spots (called 'loci') in the human genome that have been found to be associated with a susceptibility to developing Type 2 Diabetes.  These genetic variants are associated with a variety of disturbances that affect the risk of developing Type 2, including alterations in the development of the pancreas, insulin synthesis, and insulin secretion.  The genes that contribute to development of obesity (as blogged previously) likely contribute to the risk of type 2 diabetes as well, as the insulin resistance that characterizes type 2 diabetes worsens with weight gain.

In terms of the influence of these genetic variants on the risk of Type 2 Diabetes, it appears that in some cases, having two abnormal copies of these genes may as much as double the risk of getting diabetes, compared to having two normal copies of these genes. 

For some individuals, the eventual development of Type 2 Diabetes may be unavoidable, due to their genetic makeup.    However, many cases of Type 2 Diabetes are preventable, as many people develop sufficient insulin resistance to generate full blown diabetes only when they reach a state of overweight or obesity.  While obesity in itself has some genetic predisposition as well, both obesity and type 2 diabetes can be improved with dedicate attention towards a healthy lifestyle.

As for obesity genetics, our understanding of the genetic basis for Type 2 Diabetes is essential, as it will help us in better understanding the disease, finding new targets for treatment, and hopefully allowing us to improve individual strategies towards treatment and prevention.


Dr Sue Pedersen www.drsue.ca © 2011 drsuetalks@gmail.com

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After Gestational Diabetes: What's Next?

Gestational diabetes, or diabetes diagnosed for the first time during pregnancy, is a common condition, affecting approximately one in 25 pregnant women in Canada. After the baby is born, women who had gestational diabetes may be eager to leave their blood sugar concerns behind, but beware: women who have had gestational diabetes are at high risk of developing type 2 diabetes.


In pregnancy, there are several factors that contribute to the development of gestational diabetes, including increased food intake, weight gain, decreased exercise, and the production of several hormones by the placenta that make the mother more resistant to the effects of insulin. As the development of gestational diabetes identifies women whose pancreas is not able to keep up in the face of the stress of pregnancy, it also identifies women who are at future risk of developing full blown type 2 diabetes (outside of pregnancy). In fact, having had gestational diabetes increased the risk of developing type 2 diabetes later in life by up to 12 fold. Further, some cases of gestational diabetes were likely type 2 diabetics before the pregnancy started, but they did not come to medical attention until the pregnancy began.


Because the impact of undiagnosed type 2 diabetes postpartum is of serious consequence to the mother's health, and also has implications for future childbearing, it is essential that these women undergo screening for type 2 diabetes postpartum. Blood sugars will be checked following delivery in the hospital, but this alone is not enough, as diabetes can return after discharge home when normal life and eating patterns resume.


All women who have had gestational diabetes must undergo a glucose tolerance test within 6 weeks to 6 months postpartum. This involves drinking a glucose containing drink, with measurement of blood sugar before and 2 hours after the drink is taken. Checking fasting blood sugars is not enough, as this will miss 40% of type 2 diabetes in the postpartum population.


Additionally, women with previous gestational diabetes must be screened for type 2 diabetes:

* before any future pregnancies
* every 3 years, or more often, depending on other risk factors


Unfortunately, as few as 25% of women who have had gestational diabetes complete this important postpartum testing. Having undiagnosed type 2 diabetes can cause injury to blood vessels supplying vital organs including the heart, kidneys, and eyes. Having undiagnosed type 2 diabetes at the time of the next pregnancy can have devastating consequences to the fetus, including congenital malformations and miscarriage.


If you have or have had gestational diabetes, speak to your doctor to be sure that you have undergone, and continue to undergo, the appropriate screening.



Dr Sue Pedersen www.drsue.ca © 2010 drsuetalks@gmail.com


Follow me on Twitter for daily tips! @drsuepedersen


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