SMOKING-HABITS OF BLACK SOUTH-AFRICAN PATIENTS WITH DIABETES-MELLITUS

Cigarette smoking is a major arteriosclerotic risk factor, and this is enhanced by the presence of diabetes mellitus. Although smoking rates are increasing in many countries, they have been little studied. We h ave critically assessed smoking among black diabetic and general medic al patients at Baragwanath Hospital in Soweto, South Africa. As well a s direct questioning of patients, we also used urinary cotinine:creati nine ratio as an objective marker. The admitted smoking rate was 16% i n 118 diabetic patients, compared with 22 % in 105 medical patients. U sing a validated biochemical index of smoking (urinary cotinine:creati nine >1.0 mu g mg(-1)) the rates were 37 % and 33 %, respectively. Mos t of the excess however was due to women who took snuff, and when excl uded, the estimated real rates were 20 % (diabetic) and 24 % (medical) . Amongst diabetic smokers mean cotinine:creatinine ratio was higher t han in medical smokers (4.7 +/- 6.0 v 1.8 +/- 2.0 mu g mg(-1)) despite admitted similar smoking consumption. A separate control group of Bri tish smokers had a mean level of 3.6 +/- 1.3 though their consumption was twice that of the South African groups. We conclude that smoking i s common among South African black diabetic patients (20 %), though it is less than reported figures for the black general population (28 %) , and British diabetic patients (35 %). Questionnaire studies may seri ously underestimate smoking rates, though this effect is considerably less in African compared with British smokers. Urinary cotinine also a llows quantification of the 'smoking load', which is rarely reflected by admitted cigarette consumption.