Diabetes mellitus has recently been classified as a major independent risk factor for the development of coronary heart disease.1 Patients with diabetes have increased risk of cardiovascular morbidity and mortality. Diabetic patients without previous myocardial infarction have outcomes similar to non-diabetic patients who have a previous myocardial infarction.2 The importance of postprandial blood glucose is evident in the literature. Postprandial hyperglycemia (PPH) has been associated with increased risk of microvascular and macrovascular complications.3-7 The Diabetes Intervention Study had showed that PPH was an independent risk factor for myocardial infarction and cardiac death.8 We aim in our study to determine the frequency of diabetic patients, attending the outpatient medical clinic of King Abdul-Aziz University Hospital, Jeddah, Kingdom of Saudi Arabia (KSA), with optimal postprandial blood glucose level.

Methods. A cross-sectional study in which type-2 diabetic patients being followed in the outpatient medical clinic of King Abdul-Aziz University Hospital, Jeddah, KSA, from January 1999 to December 2001 were studied. The mean level of the last 2 fasting and 2-hours postprandial blood glucose (which were measured on an average of 6-12 weeks apart) was recorded. According to the expert committee report of the American Diabetes Association in 1999,9 the goal 2-hour postprandial blood glucose has to be 160 mg/dl (8.8 mmol/l) and action should be taken if it reaches 180 mg/dl (10 mmol/l); for fasting it is 120mg/dl (6.6 mmol/l) with action to be taken if it reaches 140 mg/dl (7.7 mmol/l). In 2002 a recommendation for a wider range for fasting 90-130 mg/dl (5-7 mmol/l)] was proposed and action suggested if it reached >150 mg/dl (8.3 mmol/l) and for bed time glucose it was 110-150 mg/dl (6-8.3mmol/l) and >180mg/dl (10 mmol/l).10 As we are using mmol/l unit for the measurement of plasma glucose in our hospital we classify the patients according to the 2-hours postprandial blood glucose level into 3-categories; goal <9 mmol/l, border line 9.1-10 mmol/l, poor >10 mmol/l. while for fasting; goal <7 mmol/l, borderline 7.1-8 mmol/l, poor >8 mmol/l. The following data was also collected from the study group; age, sex, body mass index (BMI), duration of diabetes, type of treatment (diet, oral hypoglycemic agents, insulin or combined), presence of hypertension (defined as blood pressure >140/90 mm Hg or if the patient is known hypertensive), hyperlipidemia (defined as low density lipoprotein (LDL) >2.6 mmol/l, high density lipoprotein (HDL) <1.1 mmol/l, triglyceride >1.7 mmol/l), history of smoking, history of ischemic heart disease (assessed by patient’s history or changes on electrophysiological studies), and mortality. The frequency of diabetic patients in each group was calculated, and the relations between them and cardiovascular risk factors and mortality were determined. Statistical analysis was carried out using the Statistical Package for Social Sciences 9.1 software. Values as mean + standard deviation were given for quantitative data and frequency for categorical variables. Chi-square was used to analyze group differences for categorical variables. For continuous variables t- test was used when comparing 2 groups. P-value <0.05 was considered significant.

Results. A total of 443 patients were enrolled in the study. Out of which 217 (49%) were males. The mean age was 54.8 ± 16.2 years and the mean BMI 25.5 ± 3.6 m2/kg. Two hundred and seventy (61% were on oral hypoglycemic agents, 133/443 (30%) on insulin, 27/443(6%) on diet and 13/443 (3%) on combined treatment. The mean fasting blood glucose for the study group was 9.7 ± 3.2 mmol/l while for 2-hour postprandial blood glucose it was 13.75 ± 5.5 mmol/l. A low frequency of patients attained the goal for fasting and 2-hour postprandial blood glucose level and most of them lie in the poor control group (Table 1). No statistically significant difference was detected between the goal group and the poor control group of 2-hour postprandial blood glucose regarding age or sex distribution while patients with poor control are more likely to have associated cardiovascular risk factors, ischemic heart disease and poor outcome (Table 2). Patients with poor 2-hour postprandial blood glucose control are also more likely to have poor fasting blood glucose control compared to goal control; 75/97 (77%) of patients with goal 2-hour postprandial blood glucose also had goal fasting blood glucose compared to 17/97 (18%) with poor fasting blood glucose (p<0.001), while 202/315 (64%) of patients with poor 2-hour postprandial blood glucose had poor fasting blood glucose versus 76/315 (24%) who have goal fasting blood glucose (p<0.001).

Discussion. Despite the significant advances in the management of coronary heart disease and the decline in mortality of cardiovascular disease in the general population by 36% in men and 27% in women over the last decade, diabetic patients continue to have a high incidence of coronary heart disease and poor clinical outcome. The decline in mortality in diabetics was only 13% in diabetic men, and it increased by 23% in diabetic women.11,12 Epidemiological and clinical evidence is mounting on the important contribution of postprandial blood glucose excursions to overall glycemic control and the association between postprandial hyperglycemia and many of the major micro- and macrovascular complications of diabetes, including retinopathy, nephropathy, and cardiovascular disease.13-17 The risk of cardiovascular disease and all-cause mortality increases with increasing postprandial blood glucose values,18-21 in addition, as indicated by the Oslo study, PPH was a predictor of fatal stroke in diabetics and the risk increased by 13% for each 18 mg/dl elevation in postprandial blood glucose level.22 Another study documented that PPH is an independent risk factor for peripheral vascular disease.23 Recent reports suggested an association between PPH and intellectual function in elderly Alzheimer’s patients.24 Our study showed a higher prevalence of ischemic heart disease and higher mortality in patients with high PPH compared to those with low levels. Several mechanisms had been proposed for the increased risk of complications that are seen in patients with PPH. The PPH is associated with hyperinsulinemia and higher plasma level of triglyceride, chylomicrons, chylomicron remnants and free fatty acids. Hyperinsulinemia has been shown to be a risk factor for cardiovascular events. The Paris prospective study found that postprandial hyperinsulinemia was a predictor for fatal cardiovascular disease.25 Similarly, the Helsinki Policeman Study revealed an independent association between fatal and nonfatal cardiovascular events and postprandial hyperinsulinemia.26 High concentration of free fatty acid is associated with endothelial dysfunction.27 High level of triglycerides is associated with low levels of HDL and preponderance of small dense LDL particles. Studies have shown that hypertriglyceridemia predicts the development of coronary artery disease and is associated with increased carotid artery atherosclerosis.28,29 Excessive postprandial blood glucose stimulates production of free radicals which are also another factor involved in the atherosclerotic process.30 Postprandial hyperglycemia has been associated with transient hypercoagulability resulting from increased thrombin production and decreased fibrinogen breakdown.31 Goal postprandial blood glucose level (<9 mmol/l) has been found in only 22% of our diabetic patients, while the majority (71%) had levels more than 10 mmol/l. Poor glycemic control is a global problem. Harris et al32 reported a rate of poor glycemic control (hemoglobin A1c >8%) in 50% of non-Hispanic black women and 45% in Mexican males. Similar results were reported by Schiel et al from Germany.33 While Azab34 reported poor fasting blood glucose control (>10 mmol/l) in 49% of diabetic patients attending Primary Health Care Centers in Riyadh, KSA, this poor glycemic control could be a result of poor compliance either due to the patients being unable to afford to buy the medications, lack of knowledge about the importance of good glycemic control or poor compliance with long time medications. Efforts should be carried out for better patients education through different media; supply of medication and proper follow up.

Received 12th May 2003. Accepted for publication in final form 5th July 2003.