Type 2 Diabetes: Separating Proven from Unproven Interventions
Am Fam Physician. 2009 Sep 1;80(5):450-452.
Type 2 diabetes is common and is becoming alarmingly more so, yet it is often misunderstood. Physicians and patients tend to think of it as a problem with glucose, when in reality it is a metabolic form of vascular disease, of which glucose comprises only a relatively small component. This point is now acknowledged in the new lipogenic model of diabetes.1 An important new look at the evidence has been presented by Shaughnessy and Slawson,2 who demonstrated that the key patient-oriented outcomes from the United Kingdom Prospective Diabetes Study (UKPDS) are not accurately reported. Of 35 reviews on the treatment of type 2 diabetes, only six accurately reflect the finding that tight control of glucose has no effect on relative or overall mortality in type 2 diabetes.2 Only a small selection of the true best evidence from the UKPDS has been passed on to physicians, and this selective sample has been heavily influenced by expert and commercial bias.
Has tight control of glucose become an inappropriate hallmark of diabetes care? Two well-done studies from 2008 (ACCORD3 and ADVANCE4 studies) confirm the basic data from the UKPDS that, at best, tight control in outpatient settings adds no significant improvement in macrovascular outcomes, and, at worst, actually increases all-cause mortality. Although there are related improvements in microvascular complications (e.g., retinopathy), the benefit is modest—a 29 percent reduction in the risk of blindness in one eye after five years of tight control.5 The problem with primary care focusing on tight glucose control is that it diverts precious time and attention from the more important outcomes in diabetes care.
There are three other de facto “standards of care” in diabetes that are not evidence-based and do not stand up to scrutiny: self-monitoring of blood glucose (SMBG), microalbuminuria testing, and Semmes-Weinstein monofilament testing for diabetic neuropathy of the feet.
Whereas SMBG creates most of the busy work for patients and physicians, its value in routine practice has never been adequately demonstrated. The ESMON and the DiGEM trials support the conclusion that SMBG has no significant effect on glycemic control and is associated with higher morbidity (e.g., higher scores on a depression subscale, higher costs, lower quality of life) and possibly higher mortality.6,7 Thus, it is unlikely to be cost-effective. The best that can be said of SMBG is that it may be of value for patients in an integrated health care setting, where it was associated with improved outcomes and lower costs of care, and perhaps for patients taking insulin.8,9
The routine practice for microalbuminuria testing meets only four out of six Frame and Carlson criteria for evaluating screening tests.10 “The recommended strategies to overcome diagnostic uncertainty by using repeated testing are based on expert opinion, are difficult to follow in primary care settings, do not improve diagnostic accuracy sufficiently, and have not been tested in a controlled trial,” concludes a 2001 systematic review.11 A 2005 review says that, “Classification of a person as normoalbuminuric must not serve to suggest that they will derive less benefit from optimal glycaemic control than a person who is microalbuminuric…. Monitoring microalbuminuria does not have a proven role in modulating antihypertensive therapy while the patient remains hypertensive.”12
Semmes-Weinstein monofilament testing of the plantar surfaces has become the preferred way to screen for diabetic neuropathy of the feet. Although multiple studies have demonstrated up to a 50 percent reduction in amputation rates by a regular “socks off ” visual inspection policy,13 no study has shown further improved outcomes from the more tedious monofilament procedure, which can involve separate testing on up to 12 different sites on the feet. Most of the available literature comments on the improved sensitivity of this approach, but fails to address the outcomes issue.
If you are routinely engaging in the four previously mentioned laudable, but unproven clinical practices for all of your patients with diabetes, you may not be paying enough attention to the things that really matter. I have created a simple alternative approach modeled after the American Diabetes Association's ABCs of diabetic care (i.e., A1C, blood pressure, and cholesterol14 ). My protocol for the routine care of type 2 diabetes excludes the four “standard” but unproven practices: tight control in outpatient settings, SMBG, microalbuminuria testing, and monofilament testing for diabetic neuropathy of the feet. Instead, it extends the ABCs to ABCDEF (see accompanying table15).
Table Basics of Evidence-Based Diabetes Care
Basics of Evidence-Based Diabetes Care
A1C: measured within six months, with a goal directed toward 7.0 percent
Blood pressure: measured every visit, with a goal of < 130/80 mm Hg
Cholesterol: low-density lipoprotein cholesterol measured within 12 months, with a goal of < 100 mg per dL (2.60 mmol per L)
MDRD: estimated GFR measured every six months, with medication adjustment or elimination (e.g., nonsteroidal anti-inflammatory drugs, metformin [Glucophage]) for estimated GFR of < 60 mL per min per 1.73 m2
Eye examination: done by an ophthalmologist on initial diagnosis and every two years,15 or on ophthalmologist-recommended schedule
Foot examination: done by visual inspection if it has been three months since the last examination
This approach covers the basics systematically and adequately while leaving time for the patient. You could expand the “D” to cover “diet” and the “E” to cover “exercise”, although this should not be necessary because lifestyle basics (e.g., diet, exercise, smoking cessation, stress management) should be addressed on every visit, or at least most visits. But this is exactly the problem. These four basics are not routinely discussed, even though they are the proven means to achieving up to 50 percent reductions in all-cause mortality.16,17 We have long known that lifestyle modification can prevent (or reverse) diabetes, reducing its incidence by up to 58 percent, and far more effectively than a drug (number needed to treat = 6.9 to prevent diabetes by lifestyle modification over an average of 2.8 years), but routine care of adults still does not emphasize lifestyle first.18 Why not? Perhaps because we are too busy focusing on SBMG, monofilament testing, testing for microalbuminuria, and striving for tight control of glucose. It is time to get back to the basics and save lives through lifestyle modification, not by performing unproven tests and procedures.
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2. Shaughnessy AF, Slawson DC. What happened to the valid POEMs? A survey of review articles on the treatment of type 2 diabetes. BMJ. 2003;327(7409):266.
3. Action to Control Cardiovascular Risk in Diabetes Study Group, Gerstein HC, Miller ME, et al. Effects of intensive glucose lowering in type 2 diabetes. N Engl J Med. 2008;358(24):2545–2559.
4. ADVANCE Collaborative Group, Patel A, MacMahon S, et al. Intensive blood glucose control and vascular outcomes in patients with type 2 diabetes. N Engl J Med. 2008;358(24):2560–2572.
5. Harris R, Donahue K, Rathore SS, Frame P, Woolf SH, Lohr KN. Screening adults for type 2 diabetes: a review of the evidence for the U.S. Preventive Services Task Force. Ann Intern Med. 2003;138(3):215–229.
6. O'Kane MJ, Bunting B, Copeland M, Coates VE, for the ESMON study group. Efficacy of self monitoring of blood glucose in patients with newly diagnosed type 2 diabetes (ESMON study): randomised controlled trial. BMJ. 2008;336(7654):1174–1177.
7. Simon J, Gray A, Clarke P, Wade A, Neil A, Farmer A, for the Diabetes Glycaemic Education and Monitoring Trial Group. Cost effectiveness of self monitoring of blood glucose in patients with non-insulin treated type 2 diabetes: economic evaluation of data from the DiGEM trial. BMJ. 2008;336(7654):1177–1180.
8. Tunis SL, Minshall ME. Self-monitoring of blood glucose in type 2 diabetes: cost-effectiveness in the United States. Am J Manag Care. 2008;14(3):131–140.
9. Schütt M, Kern W, Krause U, et al., for the DPV Initiative. Is the frequency of self-monitoring of blood glucose related to long-term metabolic control? Multicenter analysis including 24,500 patients from 191 centers in Germany and Austria Exp Clin Endocrinol Diabetes. 2006;114(7):384–388.
10. Frame PS. A critical review of adult health maintenance. Part 1: Prevention of atherosclerotic diseases. J Fam Pract. 1986;22(4):341–346.
11. Scheid DC, McCarthy LH, Lawler FH, Hamm RM, Reilly KE. Screening for microalbuminuria to prevent nephropathy in patients with diabetes: a systematic review of the evidence. J Fam Pract. 2001;50(8):661–668.
12. Newman DJ, Mattock MB, Dawnay AB, et al. Systematic review on urine albumin testing for early detection of diabetic complications. Health Technol Assess. 2005;9(30):iii–vi,xiii163.
13. Kerr CP. Improving outcomes in diabetes: a review of the outpatient care of NIDDM patients. J Fam Pract. 1995;40(1):63–75.
14. American Diabetes Association. Standards of medical care in diabetes—2009. Diabetes Care. 2009;32(suppl 1):S13–61.
15. Vijan S, Hofer TP, Hayward RA. Cost-utility analysis of screening intervals for diabetic retinopathy in patients with type 2 diabetes mellitus. JAMA. 2000;283(7):889–896.
16. Knoops KT, de Groot LC, Kromhout D, et al. Mediterranean diet, lifestyle factors, and 10-year mortality in elderly European men and women: the HALE project. JAMA. 2004;292(12):1433–1439.
17. King DE, Mainous AG III, Geesey ME. Turning back the clock: adopting a healthy lifestyle in middle age. Am J Med. 2007;120(7):598–603.
18. Knowler WC, Barrett-Connor E, Fowler SE, et al., for the Diabetes Prevention Program Research Group. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med. 2002;346(6):393–403.
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