Review: Several interventions reduce complications in type 2 diabetes mellitus
ACP J Club. 1998 Mar-April; 128:30. doi:10.7326/ACPJC-1998-128-2-030
Vijan S, Stevens DL, Herman WH, Funnell MM, Standiford CJ. Screening, prevention, counseling, and treatment for the complications of type II diabetes mellitus. Putting evidence into practice. J Gen Intern Med. 1997 Sep;12:567-80.
To review the effectiveness of various interventions to prevent, screen for, and treat complications in patients with type 2 diabetes mellitus.
Studies were identified by using MEDLINE (1976 to 1996) with the search terms diabetes mellitus and non-insulin-dependent in the topic areas retinopathy, nephropathy, neuropathy, hypertension, lipids, triglycerides, low-density lipoprotein, smoking, blood glucose, foot care, self-management, education, and preconception care and pertaining to prevention, treatment, and control. Quality filters included the terms clinical trial, controlled clinical trial, randomized controlled trial, cohort study, multicenter trial, and meta-analysis. Other data sources were consensus statements, bibliographies of relevant papers, and consultation with experts.
Studies were selected if they had a sample size > 30 and follow-up of > 3 months. Randomized controlled trials (RCTs) were preferred.
Selected studies were evaluated by each author, and consensus recommendations were developed.
Meta-analyses and reviews found that self-management education improves knowledge, skill, self-care behaviors, psychosocial outcomes, and metabolic control. Prophylactic aspirin has similar cardiovascular benefits and adverse effects for patients with and without diabetes. Antihypertensive therapy reduces mortality in persons with diabetes, and a target blood pressure of 130/85 has been recommended by experts. Only low-dose diuretics have been directly shown to decrease mortality in persons with diabetes. Angiotensin-converting enzyme (ACE) inhibitors (in patients with nephropathy) and β-blockers (after myocardial infarction) may have other specific benefits. Smoking and diabetes are synergistic risk factors for atherosclerosis. Several observational studies suggest that improved glycemic control may reduce retinopathy, nephropathy, and neuropathy in type 2 diabetes, and a Japanese RCT found that improved glycemic control reduced microvascular complications in type 2 diabetes. These results, however, may not be generalizable.
Multicenter RCTs show that laser therapy reduces vision loss in patients with proliferative retinopathy and macular edema. RCTs show that systemic blood pressure control and ACE inhibitors independently reduce renal disease progression in type 2 diabetes. Early detection of diabetic neuropathy leads to fewer admissions for foot ulcers and fewer amputations. An RCT and a cohort study each found that combined patient education and physician surveillance of foot care reduced serious foot lesions.
Randomized controlled trials and cohort studies show that specific interventions are effective for preventing and treating macrovascular and microvascular complications in patients with type 2 diabetes mellitus.
Source of funding: Not stated.
For article reprint: Dr. C.J. Standiford, University of Michigan Medical Center, 3116 Taubman Center, Box 0376, Ann Arbor, MI 48109-0376, USA. FAX 734-936-8944.
Type 2 diabetes continues to be associated with considerable human and economic costs. The Diabetes Control and Complications Trial (1) showed, in a large RCT, that tight glycemic control helped prevent microvascular complications in patients with type 1 diabetes. Keen interest remains, however, about whether interventions, glycemic or otherwise, can prevent microvascular and macrovascular complications in patients with the far more common type 2 diabetes.
Many expert groups have published guide-lines about the appropriate management of diabetes. Generally, these have been based on extensive literature reviews by experts in the field, but they have not been “evidence-based”; that is, they have not incorporated explicit methods to evaluate the supporting evidence and to grade specific recommendations according to the strength of the evidence.
Vijan and colleagues have attempted to provide evidence-based recommendations. They did a thorough literature review and came up with a series of recommendations to aid in the screening, counseling, and treatment of patients with type 2 diabetes. Their conclusions can be questioned on some minor points, but these are in areas where evidence is relatively weak.
The strength of this paper is that it highlights the importance of glycemic control and other interventions, such as control of hypertension and lipid levels, that can decrease the burden of disease associated with type 2 diabetes. Several large clinical trials (e.g., the United Kingdom Prospective Diabetes Study and the Heart Outcomes Prevention Evaluation) now underway should help resolve some unanswered questions. In addition, several drugs are being developed (e.g., aldose reductase inhibitors, aminoguanidine, and protein kinase C inhibitors) that may turn out to be more specific inhibitors of the complications.
Lawrence A. Leiter, MD
St. Michael's HospitalToronto, Ontario, Canada
Lawrence A. Leiter, MD
St. Michael's Hospital
Toronto, Ontario, Canada
1. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. The Diabetes Control and Complications Trial Research Group.N Engl J Med. 1993; 329: 977-86.