Tempest in a teacup
“This is large, observational data. It’s not a randomized controlled trial so there’s plenty of room for data to be misunderstood,” warned Matt Sydes, MSc, professor of clinical trials & methodology at the MRC Clinical Trials Unit, University College London.
“Everyone drinks fluids. If there is an effect here (and that’s a big if), it might be not about the tea they drink, but about what they don’t drink. One can’t tell at the moment. It seems unlikely that a large randomized controlled trial could be done to disambiguate” added Dr. Sydes
“Being only a conference abstract, it is difficult to assess the quality of this research,” Baptiste Leurent, PhD, a medical statistician also working at University College London, said. Not only was the cohort study observational, so were all the other studies included in the meta-analysis, he pointed out.
“Therefore, no cause-effect conclusions can be drawn. The association could simply be due to other factors, such as those drinking more tea having a healthier lifestyle. It does not seem that the authors tried to control for confounders, which is usually difficult in meta-analysis,” Dr. Leurent said.
“There is reason to be a bit skeptical at this point; we really need to have the full details to assess it properly,” said Jonathan Cook of the Centre for Statistics in Medicine at the University of Oxford (England). “It’s a fair attempt to look at this, but not cutting edge, [using] fairly standard approaches.”
Similar studies have shown a reduced risk associated with coffee drinking, noted Duane Mellor, PhD, a registered dietitian and senior teaching fellow at Aston University in Birmingham.
“The important take-home message is that lifestyle is important in managing risk of developing type 2 diabetes,” Dr. Mellor said.
“That includes choosing low-calorie drinks including mainly water as well as unsweetened tea and coffee as your drinks of choice as part of a healthy lifestyle.”
The study was funded by the Young Talents Project of Hubei Provincial Health Commission, the Science and Technology Research Key Project of Education Department of Hubei Province, the Sanuo Diabetes Charity Foundation, and the Xiangyang Science and Technology Plan Project, all based in China. Dr. Li had no conflicts of interest to disclose. Dr. McConway is a Trustee and on the advisory committee of The Science Media Centre. Dr. Sattar has consulted for many companies that make diabetes and cardiovascular drugs and has been involved in multiple trials of lifestyle approaches for the prevention and remission of diabetes. Dr. Sydes, Dr. Leurent, Dr. Cook, and Dr. Mellor had no conflicts of interest to report.