Later this year the National Service Framework (NSF) on diabetes will be published with an implementation date from April 2002. The goals of this NSF are to:

• decrease the incidence of type 2 diabetes
  
• improve health outcomes of people with diabetes
  
• reduce unacceptable variations in the quality of services for people with diabetes

Diabetes is a common, chronic disease that can have serious complications. Life expectancy may be reduced by between 10 and 20 years in people with diabetes. The risk of cardiovascular mortality is two to three times higher in men with diabetes and three to five times higher in women with diabetes than in people without diabetes. Diabetes occurs significantly more often in non-Caucasian ethnic communities, up to five times more often in people of Asian descent and up to four times more often in people of African and African Caribbean descent. According to the Audit Commission report 'Testing Times' (1) the number of people with diabetes is rising rapidly with diabetes affecting 3% of the population, but 25% of Asian people over 60. Many people with diabetes remain undiagnosed and the UK figure may double to 3 million by 2010 because of rising obesity and an ageing population.

There is strong causal evidence for the impact of physical inactivity on an ever-broadening variety of health problems, including diabetes. Thirty minutes of moderate intensity physical activity on at least five days a week can lead to substantial benefits, however surveys show that six out of ten men and seven out of ten women are not active at this level. Many GPs are participating in exercise referral schemes and in order to raise standards and improve the quality of local schemes, the Department of Health has published a National Quality Assurance Framework on Exercise Referral Systems (2).

Cardiovascular risk factors in people with diabetes include conventional risk factors (age, prior cardiovascular disease, smoking, hypertension, dyslipidaemia, sedentary lifestyle, family history of premature cardiovascular disease) and more diabetes specific risk factors (elevated urinary protein excretion, poor glycaemic control). Interventions that can improve cardiovascular outcomes in people with diabetes include (3):

• Aggressive lowering of blood pressure in people with diabetes who have hypertension reduces cardiovascular morbidity and mortality. However it is not clear whether any one major class of antihypertensive medication is superior to others.
  
• Statins and fibrates are effective in primary and secondary prevention of cardiovascular disease in people with diabetes and dyslipidaemia.
  
• Aspirin is effective in primary and secondary prevention of cardiovascular disease in people with diabetes. In patients with hypertension blood pressure should be controlled before prescribing aspirin.

The Heart Outcomes Prevention Evaluation study (HOPE) compared ramipril to placebo in people with and without diabetes, who were aged 55 years or older and who had a history of cardiovascular disease or diabetes plus at least one other cardiovascular risk factor. HOPE was stopped 6 months early (after 4.5 years) because of a consistent benefit of ramipril compared with placebo. In the MICRO-HOPE substudy of 3,577 people with diabetes (4), ramipril lowered the relative risk of a major cardiovascular event by 25% (myocardial infarction, stroke or cardiovascular death) and the absolute risk by 4.5%. The relative risk of overt nephropathy was reduced by 24% (absolute risk reduction 2.0%). The benefit was apparent irrespective of whether participants had a history of cardiovascular events, hypertension, or microalbuminuria, were taking insulin or oral antidiabetic drugs, or had type 1 or type 2 diabetes.

The UK Prospective Diabetes Study was the largest and longest study of type 2 diabetes. Its main messages were:

• Type 2 diabetes is a progressive disease and should never be considered a mild form of diabetes.
  
• Intensive treatment of type 2 diabetes with sulphonylureas and/or insulin resulted in a 25% relative risk reduction in microvascular endpoints.
  
• Metformin should be the drug of choice for overweight patients, assuming they have no contra-indications. Patients assigned metformin had a 32% relative risk reduction of developing any diabetes related end points, both microvascular and macrovascular.
• Tight control of blood pressure reduces the risk of any non-fatal or fatal diabetic complication and of death related to diabetes. Deterioration in visual acuity was also reduced making the reduction of blood pressure a high priority in patients with type 2 diabetes.
  
• Multiple drug combinations may be necessary to achieve blood pressure targets.

The introduction of the thiazolidinediones, rosiglitazone and pioglitazone, has increased the range of antidiabetic drugs. NICE appraisals of these two drugs give advice on where they should be used in the management of type 2 diabetes5,6. Metformin or a sulphonylurea should be offered as monotherapy followed by a combination of metformin and a sulphonylurea. If the patient is unable to take this or there is high blood glucose despite this then either rosiglitazone or pioglitazone may be offered in combination as an alternative to injected insulin. The preferred combination is metformin with rosiglitazone or pioglitazone particularly for the obese.

The following prescribing data are given for the quarter to March 2001 unless stated otherwise. Charts 1 and 2 show that over the last five years prescribing of insulins has increased by 57% to 757,000 items per quarter whilst costs have risen by 96% to £27.2 million. Over the same period prescribing of oral antidiabetic drugs has increased by 71% to 2.3 million items per quarter and costs by 137% to £14.0 million.

Insulins are now mainly prescribed as the newer injection devices and their cartridges (a 157% increase in their prescribing over the last five years, whilst the prescribing of 10ml vials has fallen). More intermediate and long acting insulins are prescribed than short acting insulins, accounting for around 75% of both prescribing and cost (586,000 items and £20.5 million per quarter).

References

1. Testing Times A Review of Diabetes Services in England and Wales. Audit Commission April 2000
2. Department of Health. Exercise Referral Systems: A National Quality Assurance Framework 2001
3. Sigal R. Cardiovascular disease in diabetes. Clinical Evidence Issue 4, BMJ Publishing Group, December 2000
4. Heart Outcomes Prevention Evaluation (HOPE) Study Investigators. Effects of ramipril on cardiovascular and microvascular outcomes in people with diabetes mellitus: results of the HOPE study and MICRO-HOPE substudy. Lancet 2000; 355: 253-259
5. National Institute for Clinical Excellence. Guidance on rosiglitazone for type 2 diabetes mellitus. Technology Appraisal Guidance No. 9, August 2000
6. National Institute for Clinical Excellence. Guidance on pioglitazone for type 2 diabetes mellitus. Technology Appraisal Guidance No. 21, March 2001