Objective: To study the role of baseline risk factors in predicting the onset of diabetes among essential hypertensive patients with metabolic syndrome (MS) and to evaluate an ideal therapeutic regime that could reduce the risk factors and risk of onset of diabetes.
Methods: A randomized parallel clinical trial in essential hypertensive patients of grade 1 or 2 was conducted. Two of the three components (1) increased waist circumference and/or BMI; (2) increased triglycerides (TG) and/or decreased high-density lipoprotein cholesterol; (3) impaired glucose tolerance (IGT) were present define the MS. The three intervention therapy groups were: indapamide + fosinopril (I + F, n = 151); atenolol + nitrendipine (A + N, n = 160); atenolol + nitrendipine + metformin (A + N + M, n = 152). Each case was followed-up monthly and the dosage of medicine taken be adjusted according to their BP level. The plasma glucose during fasting and two hours after taking 75 g glucose orally was also measured every six months. The new onset of diabetes was diagnosed according to the criteria. OGTT, insulin release test, lipid analysis, body weight and waist circumference were measured again at the last follow-up.
Results: (1) The lowering of BP was similar among the three groups (P > 0.05). 23 new diabetes onsets occurred, being 10 in group I + F and 8 in group A + N and 5 in group A + N + M, respectively (P > 0.05); (2) Proportions of patients' risk factors decreased significantly in group A + N or A + N + M, e.g. the proportions of high TG in each group reduced by 14.7% and 9.3% respectively (P < 0.05), the central fat distribution reduced by 16.7% and 15.9% respectively (P < 0.05) and the IGT reduced by 6.6% and 29.6% respectively (P < 0.05). However no changes were found in group I + F; (3) After 1 year and 5 months' follow-up, the proportions of main risk factors (high TG, central fat distribution and IGT) in the three groups were 91%, 96%, 83% and 90%, 88%, 47%, respectively. The difference of IGT was significant between two groups (P < 0.01) and the proportions of having three risk factors were 70% and 31% in the two groups (P < 0.01); (4) I + F group was better than A + N group in reduction of TG and central fat distribution. And A + N + M group improved in all risk factors.
Conclusions: IGT alone or combined with increased TG plus abdominal obesity are the most important risk factors in predicting a new onset of diabetes among essential hypertensive patients with MS. Metformin in combination with atenolol plus nitrendipine can significantly prevent the onset of diabetes as well as improve patients' metabolic abnormality.