An externality is a cost or benefit of aneconomic activityexperienced by an unrelated third party. The external cost or benefit is not reflected in the final cost or benefit of a good or service. Therefore, economists generally view externalities as a serious problem that makes markets inefficient, leading to market failures. The externalities are the main catalysts that lead to the tragedy of the commons.

11 What does BM mean in relation to blood sugar monitoring?

12 What is the role of urine examination in diabetic control?

13 Diabetes and diet: could the authors of my favourite medical text please advise whether or not it is acceptable to have controlled quantities of refined sugar, providing the total calorie intake is kept under control?

14 Do non-obese patients with impaired fasting glucose, i.e. a glucose level of 6.1-6.9 mmol/L, need drug treatment with biguanides if lifestyle modifications fail to normalize?

15 Do non-obese patients with impaired glucose tolerance (but not fulfilling the criteria for diabetes mellitus) need drug treatment with biguanides if lifestyle modifications fail to normalize their post-prandial blood glucose measurements?

16 It is the Muslim month of fasting currently. I would be grateful if you could advise on how to adjust the insulin regimen of a type 1 diabetic patient, for example a 21-year-old girl who is on subcutaneous Actrapid (short-acting soluble insulin) 22 units t.d.s.

17 I would like to know more about the use of the glitazone group in type 2 diabetes: its action, side-effects, precautions taken on using them.

18 In a patient receiving oral antidiabetics, should the drug be administered just after taking the blood sample for fasting blood glucose level (and before a meal), or just prior to the sample being taken?

19 What oral antidiabetics are safe in pregnancy?

20 Is it necessary to put all type 2 diabetics on aspirin?