The incidence of new onset diabetes among patients with hypertension is unknown, though the prevalence has been said to be between 15 and 18%.1 In rural Sweden the mean annual incidence of diabetes has been recorded as 3.46 per 1000 of the total population,2 and a prevalence in England of 2.5% has been reported.3
In our practice of 10 778 patients, we have included annual glucose measurement as part of the annual review of hypertensive patients for 6 years. We have studied the incidence of new cases of impaired fasting glucose, impaired glucose tolerance or diabetes mellitus in our patients with hypertension, who do not have established ischaemic heart disease.
Patients registered with the practice, who have hypertension, but did not have established ischaemic heart disease, and who were not known to have diabetes mellitus, impaired glucose tolerance, or impaired fasting glucose, on 1 March 2002, were examined. The incidence of new cases of abnormal glucose metabolism diagnosed in this group over the period 1 March 2002 to 31 August 2003 was determined. Of 568 patients tested 1.4% were found to be diabetic and another 1.6% to have impaired glucose tolerance or impaired fasting glucose.
Three per cent of patients tested in the 18-month period were shown to have abnormal glucose metabolism, giving an annual incidence of 2%. Of these, nine patients (53% of those diagnosed) had had a glucose level of less than 6 mmol/l recorded during the previous 3 years; this and the fact that the practice had a prevalence of diabetes of 3.9% at the start of the study period, suggests that our findings are not just a reflection of previous under-diagnosis.
Early diagnosis of abnormalities of glucose metabolism in patients at increased cardiovascular risk because of hypertension should allow early intervention and risk modification. We believe that glucose measurement should be included as part of the annual review of patients with hypertension, and the advent of the GPs' new contract provides opportunities for this to be done.
- © British Journal of General Practice, 2004.
