Tea and coffee drinkers have a lower risk of developing type 2 diabetes

Australian researchers conducted a systematic review and meta-analysis that pooled data from more than 30 studies of the association between tea and coffee consumption and the risk of developing type 2 diabet. About a million of participants were involved.

They found that "high intake of coffee, decaffeinated coffee, and/or tea is associated with a reduction in the risk of new-onset type 2 diabetes" and the compound magnesium and antioxidants in tea and coffee may be involved.

Critics said the studies lacked sufficient data on the effects of these beverages or their components on measures of hyperglycaemia and insulin sensitivity, therefore the mechanisms involved is still unknown. It may not be possible to generalise these findings to other populations because only a small number of particpants were non-white.

Further research into the effect of these beverages on diabetes is warranted, but it is advised that people should not increase their tea or coffee consumption based on these findings.

Source: Huxley R, Man Ying Lee C, Barzi F, et al. "Coffee, Decaffeinated Coffee, and Tea Consumption in Relation to Incident Type 2 Diabetes Mellitus". Arch Intern Med 2009; 169: 2053-2063

Calmer approach to Avandia : The Lancet

Since the NEJM paper ( see posting on 25 May 2007) was published on May 21, frightened diabetes patients flooded their doctors with calls, many patients have stopped taking Avandia or switched to a rival drug Actos although some experts caution there is no urgent need for diabetes patients to stop taking Avandia.

The Lancet published an editorial online on May 23, 2007 to point out that there are important weaknesses in Nisson's meta analysis and call for "a calmer and more considered approach to the safety of Rosiglitazone" in response to the alarm raised by Dr Steven Nisson in NEJM.

According to The Lancet, the 2 most reliable studies to inform decision-making are ADOPT (published by NEJM) and DREAM (published by The Lancet). Although the results of these studies "indicate the need for more reliable information about rosiglitazone's safety", patients should calm down and wait for the results of the RECORD trial, a multi-centre study designed to monitor cardiac risk.

Avandia and myocardial infarction

A leading cardiologist, Steven Nissen, found that Avandia (generic name: rosiglitazone), a diabetes drug, "was associated with significant increase in the risk of myocardial infarction and with an increase in the risk of death from cardiovascular causes that had borderline significance."

The study concluded that despite the study's limitation, " patients and providers should consider the potential for serious adverse cardiovascular effects of treatment with rosiglitazone for type 2 diabetes."

His findings were based on an analysis of 42 RCTs and published online on May 21 by NEJM. "Effect of Rosiglitazone on the Risk of Myocardial Infarction and Death from Cardiovascular Causes". The article will appear in the June 14 issue of the Journal.

Avandia is a top-selling diabetes drug manufacturered by GlaxoSmithKline, introduced in 1999 and is widely used to lower blood glucose levels in patients with type 2 diabetes mellitus. Nissen’s analysis on Avandia has caused the Glaxo stock down more than 6% in midday trading.

Dr. Nissen is a strong critic on drug safety, he and colleague, Eric Topol, a well-known cardiologist, raised concerns about the safety of Vioxx in JAMA in 2001 that led to the withdrawal of the drug from the market in 2004. Dr Topol lost his job after testimony against the drug manufacturer Merck in federal trial.