The uses of biguanides in diabetes mellitus

The concomitants of raised blood sugar: studies in newly-detected hyperglycaemics: II. Urinary albumin excretion, blood pressure and their relation to blood sugar levels

The albumin excretion rate following an oral glucose load was measured, using a sensitive radio-immunoassay method, in three groups drawn from the population of Bedford. The three groups – normal,borderline diabetic and diabetic – were classified by the level of the blood sugar 2 hours after the 50 -g glucose load. The degree of albumin excretion was positively correlated with the 2-hour blood sugar level, suggesting that hyperglycaemia may cause renal functional abnormality, which may be present at or before the time of diagnosis. In the diabetic group, only, the degree of albumin excretion was also positively correlated with the height of the blood pressure.

The Value of Screening for Diabetes in Patients with Skin Sepsis

Four hundred and eighty-two patients with spontaneous skin and superficial sepsis and 291 controls of similar age and sex underwent random capillary blood glucose measurements in order to assess whether screening for diabetes in patients presenting with skin sepsis to an Accident & Emergency Department detects a greater number of cases than that present in the background population. All subjects with a concentration >7.8 mmol/l were subsequently followed up with a 75 g oral glucose tolerance test. Forty-two (8.7%) of the 482 skin sepsis patients had a capillary blood glucose >7.8 mmol/l compared to eight (2.7%) of the 291 without sepsis (χ2=9.71, P<0.002). Of these, 26 of the skin sepsis group and 7 of the control group attended for follow up. Of those who attended, 13 of the skin sepsis group had an abnormal glucose tolerance test (seven diabetes, six impaired glucose tolerance — IGT) compared to two (one diabetes, one IGT) of the control group (χ2=2.87, P<0.1). The difference in cases of frank diabetes between the two groups was not statistically significant. Of the total eight diabetic cases identified, five (on direct questioning) had symptoms of hyperglycaemia (thirst, polyuria and/or weight loss) and two of the others were obese, one of whom had documented ischaemic heart disease. Thus, while most cases of diabetes in patients with skin sepsis could be detected by specifically asking about hyperglycaemic symptoms and performing a blood glucose estimation when these are present, we suggest that the screening of patients with skin sepsis over 40 years of age provides an opportunistic method of screening. This strategy should yield clinically significant numbers of abnormal cases.

Adverse cardiovascular effects of sulphonylurea drugs. Clinical significance

Sulphonylureas are widely used in the treatment of diabetes mellitus. Since the publication of the University Groups Diabetes Program (UGDP) results the discussion on their possible cardiovascular side effects has been lively and sometimes even passionate. The initial UGDP findings about the adverse effects of tolbutamide on the cardiovascular system have been criticised, particularly for shortcomings in the study design. The results of other epidemiological studies of the sulphonylurea effects on cardiovascular morbidity and mortality published this far have been contradictory. This is understandable because the factors involved are very complex. Most of these studies have used tolbutamide only, and the findings cannot necessarily be directly extrapolated to other sulphonylureas. Only properly performed prospective studies may provide further information on this issue. High concentrations of several sulphonylureas may have inotropic effects on heart muscle in in vitro animal models, but human studies performed in vivo do not support the view of clinically significant inotropy for sulphonylureas. High concentrations of tolbutamide or glibenclamide (glyburide) may affect the myocardial metabolism in isolated organs, but the possible clinical significance of these findings remains unknown. Some epidemiological and experimental studies have associated oral antidiabetic treatment with the occurrence of cardiac arrhythmias or increased digitalis toxicity. Only a few results are available, and there may be differences between the sulphonylureas in this respect. Antiaggregatory properties have been postulated for some sulphonylureas. Gliclazide, in particular, has been studied, but some other compounds of this class have also been effective in short term studies. If confirmed, these effects on haemostasis would be noteworthy. The sulphonylurea effects on serum lipids, especially on HDL-cholesterol, have been discussed widely during the last few years. Decreases in HDL-cholesterol concentrations were suggested to be associated with sulphonylurea therapy. However, these findings were not confirmed in recent cross-sectional and longitudinal studies performed with different sulphonylureas. Chlorpropamide, and to a lesser extent tolbutamide, may cause dilutional hyponatraemia and aggravate existing heart failure. Glibenclamide may increase the clearance of water in the kidney.

Metformin reduces post-prandial insulin needs in type I (insulin-dependent) diabetic patients: assessment by the artificial pancreas

It has been suggested that biguanides should be used in Type 1 (insulin-dependent) diabetic patients in order to diminish insulin requirements and reduce the chances of insulin reactions. The efficacy of these compounds in such patients has been controversial. We have studied the effect of metformin (850 mg) given at 08.00 h in diminishing insulin needs after a 60 g carbohydrate mixed meal taken at 12.00 h, using an artificial pancreas and a sequential analysis of the results. The morning test dose of metformin or placebo was preceded by 48 h treatment with metformin (850 mg twice daily) or placebo. After the eighth patient a 26% saving of insulin need was demonstrated in the metformin-treated group (p less than 0.01). Metformin is thus effective in reducing post-prandial insulin needs in Type 1 diabetic patients, although its use in such circumstances requires consideration of several other issues.

Sulphonylureas and cardiovascular disease: a problem for few diabetics

Because of the doubts cast on the safety of the sulphonylureas we analysed 1000 consecutive referrals to a diabetic clinic to identify the number of new patients equally suitable for treatment with a sulphonylurea or insulin. After excluding previously diagnosed and treated diabetics and those with a non-diabetic glucose tolerance test there were 531 new diabetics. Youth and insulin dependency, old age or obesity accounted for 390. A further 40 required diet alone, 50 had concomitant disease or socio-domestic circumstances influencing treatment choice, and 10 had secondary diabetes. Thus, only 41 diabetics (7.7% of new patients or 4.1% of total clinic referrals) appeared suitable for optional sulphonylurea or insulin therapy. We conclude that there are relatively few diabetics for whom the questionable safety of the sulphonylureas poses a therapeutic problem, and equally few who would be available for any further long-term, random-allocation trials of their effects upon the cardiovascular system.

Hyperglycaemia and diabetes mellitus

Recommended criteria for the diagnosis of maturity-onset diabetes mellitus based on glucose tolerance tests vary considerably; none are derived from long-term observations of the further development of different degrees of glucose intolerance. Evidence from several epidemiological investigations suggests that the risk of specific diabetic complications becomes important only in people with capillary whole-blood sugar concentrations exceeding 200 mg/dl 2 hours after a 50 g oral glucose load, who have overnight fasting blood-sugar concentrations usually exceeding 110 mg/dl. Lesser degrees of glucose intolerance may, nevertheless, indicate an additional risk of atherosclerotic arterial disease. Assessment of "borderline diabetics" should, therefore, include and evaluation of other known risk factors for arterial disease and any treatment programme should be determined in the light of these as well as by the degree of glycaemia.