Tips from gaining health

Research due in an upcoming issue of the British Medical Journal found that smokers had a greater risk of developing glucose intolerance than people who never smoked. But another finding of the study is raising eyebrows - that people exposed to secondhand smoke also experienced an increased risk for the condition.

The study, begun in 1985, followed 4,572 young men and women (age 18 to 30 at baseline) in four American cities for up to 15 years.

After adjusting for confounders (factors that could also influence development of glucose tolerance - age, sex, race, education, income, blood pressure, body mass index, triglycerides, and alcohol intake), researchers found, when compared to people who never smoked and had no passive smoke exposure:

• Current smokers (average 10 cigarettes/day) had a 65% greater risk of developing prediabetes.
  
• People who never smoked but were exposed to secondhand smoke (average 12.6 hours/week) had a 35% greater risk of developing prediabetes.

Prediabetes, also known as impaired glucose tolerance, was recorded when serum glucose ≥ 100 mg/dl and < 126 mg/dl. (Diabetes is diagnosed when fasting serum glucose ≥ 126 mg/dl.) Most people with prediabetes will develop full blown diabetes unless they make lifestyle changes.

Researchers said substances in cigarette smoke which are damaging to the pancreas may be present in higher concentrations in secondhand smoke, since passive smoke is produced under different temperatures and chemical conditions.

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Some news summaries:
Secondhand Smoke Linked to Diabetes Risk

Passive Smoke Could Prompt Diabetes Precursor: Report

Smoking Linked to Glucose Intolerance in Young Adults

For the study abstract:
Active and passive smoking and development of glucose intolerance among young adults in a prospective cohort: CARDIA study

For the study (pdf):
Active and passive smoking and development of glucose intolerance among young adults in a prospective cohort: CARDIA study

My previous post discussed the link between smoking and death from heart and lung diseases (and showed benefit for quitting). Heres a study, actually a study of studies or a meta-analysis, from 5 months ago that reasserted the often observed link between smoking and type 2 diabetes:

Active Smoking and the Risk of Type 2 Diabetes, JAMA, December, 2007

Of the 25 studies included in this analysis, 24 reported a positive association between smoking and diabetes, specifically:

"The pooled adjusted RR was 1.44."

An RR (Relative Risk) of 1.44 means that there was a 44% increased risk for developing diabetes among active smokers vs. non-smokers. Among heavy smokers, the risk increased to 61%:

"The risk of diabetes was greater for heavy smokers (≥20 cigarettes/day; RR 1.61) than for lighter smokers (RR 1.29) and lower for former smokers (RR 1.23) compared with active smokers, consistent with a dose-response phenomenon."

The link was so consistent that the authors stated there was "no need for further cohort studies to test this hypothesis." They recommended instead "that future studies focus on plausible causal mechanisms or mediating factors such as obesity, lack of physical activity, dietary habits, and stress levels."

One mechanism they noted which has appeared in previous studies is smokings link to insulin resistance or inadequate insulin secretion - a mechanism which should bear scrutiny in future investigations.
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