Analysis of quality management and analysis system data for England and Scotland in 2004/5 suggested diabetes care was poorest when provided by smaller GP practices.
Because small practices are often found in deprived areas, this could mean patients who most need high-quality care are less likely to receive it, according to the researchers.
The difference in achievement of target for BP, HbA1c and cholesterol between small and large practices was less than 5 per cent.
But in practices with list sizes smaller than 3,000, only 78.2 per cent of patients underwent retinal screening, compared with 86.1 per cent in practices with lists of 10,000-plus. Similarly, 71.2 per cent of patients at small practices underwent neuropathy testing, compared with 80 per cent at the largest.
Peripheral pulse testing was carried out in 73.1 per cent of diabetics at small practices, compared with 81.1 per cent at practices with the biggest list size.
Although most practices in deprived areas were less likely to achieve national treatment targets, this trend was particularly marked in small practices.
Dr Michael Taylor, chairman of the Small Practices Association, said the comparison was unfair, because small GP practices in deprived areas were often run under PCT Medical Services (PCTMS) contracts.
'I'm happy for there to be large and small practices, but this study doesn't compare like with like,' he said. 'This is a major gaffe in this paper.'
Lead researcher Christopher Millet, from the department of primary care and social medicine at Imperial College, London, admitted that the study did not take account of PCTMS and that further research was needed.What do you think? Comment below or email GPletters@haymarket.com