Reduction of diabetic complications with intensive blood glucose control: A systematic review of the literature

Aim: To examine whether intensive glucose control reduces complications including renal insufficiency, visual impairment, neuropathy, or cardiovascular disease in patients with type 2 diabetes. Methods: Systematic review of randomized control trials and prospective observational studiesinvestigating the effect of intensive blood glucose control on diabetic complications in patients with type 2 diabetes published between 1990 and 2007. Studies were identified using MEDLINE, The Cochrane Library and CINAHL. Reference lists of relevant papers were hand searched for further articles. Results: Two good quality studies met inclusion criteria, UKPDS 33 and UKPDS 35. In UKPDS 33, median HbA1c in the intensive group was 7.0% (95% CI: 6.2-8.2) and the conventional group was 7.9% (95% CI: 6.9- 8.8). The reduction in HbA1c correlated with a decrease in certain diabetic complications including blindness and amputation. There was no difference between the control and intervention groups for worsening visual acuity, absent ankle or knee reflexes, orthostatic hypotension, erectile dysfunction, silent MI, absent peripheral pulses, or evidence of peripheral vascular disease detected by doppler. A 16% reduction in myocardial infarction was border line insignificant with p = 0.052. In UKPDS 35, for each 1% reduction in A1c level, there was an associated decrease in risk of 37% for microvascular endpoints, 43% for amputations or death from peripheral vascular disease, and 14% for myocardial infarction. The incidence of a myocardial infarction was two to three times that of microvascular complications around normal values of A1c, but as the A1c reached higher values in near the maximum range, the risk of these complications were similar. Conclusions: Limited evidence is available to support the treatment of all patients with type 2 diabetes with intensive blood glucose control. Age, duration of disease, co-morbid complications, and compliance are some of the factors to be considered in A1c target values and these should be determined on an individual patient basis. Several trials are currently underway to provide more insight into the benefits of intensive glucose control to near-normal values. Studies to determine the magnitude of any benefit to lower A1c values to normal and below are not available. Keywords: Diabetes Mellitus, Type 2, Hemoglobin A, Glycosylated, Complications, Blood Glucose ControlMaster of Public Healt