An Evidence-based Approach to Evaluating and Managing Type 2 Diabetes

New evidence supports many current approaches to diabetes management, but also challenges the efficacy of several common practices.

According to Steven L. Milligan, MD, FAAFP, there have been many new developments and research findings in the last several years that have challenged how clinicians evaluate and treat patient with type 2 diabetes mellitus. During his presentation, “Diabetes Mellitus Treatment — Fundamentals: An Evidence-based Approach,” Wednesday at the 2010 AAFP Scientific Assembly, Milligan used an interactive case-based approach to highlight key points that clinicians should consider when evaluating and diagnosing patients for type 2 diabetes and devising a treatment regimen. Throughout the session, he posed questions concerning the next steps the audience would take when examining and treating a hypothetical female patient.

Milligan began the session by asking the audience to use those ubiquitous little audience-response keypads to rate their comfort level when it comes to managing patients with type 2 diabetes. Nearly 80% of the audience agreed (51%) or strongly agreed (28%) with the statement “I am comfortable managing patients with diabetes.” From there, he outlined the hypothetical patient’s key clinical factors and test scores: patient is a 40-yer old woman who hasn’t seen a doctor since the birth of her last child six years ago; she is currently on a statin (simvastatin); she is a non-smoker who gets little to no regular exercise; she has gained 7.5kg since age 18. Both of the patient’s parents are overweight and have type 2 diabetes.

Given this patient’s clinical presentation, Milligan asked the audience to estimate the impact of her weight gain on her risk for developing type 2 diabetes. Most of the audience correctly responded that this weight gain doubles the patient’s risk for developing type 2 diabetes. To underscore this point, Milligan noted that there is solid evidence showing that not only is an increase in weight after age 18 correlated with significant increased risk of developing diabetes, but just as importantly, there is also evidence showing that a significant decrease in weight is associated with a significantly decreased risk of developing diabetes.

This patient’s weight gain and lack of exercise can have a significant impact on her risk for diabetes; her BMI of 25.9 (which qualifies her as overweight, not obese) raises her risk threefold for developing diabetes, said Milligan. Further, the data shows that a BMI of 30 or greater (which would qualify as obese) increases a patient’s diabetes risk by nine times. Milligan also noted that physical inactivity, apart from being overweight, has an impact on diabetes risk. Data shows that an inactive and overweight patient (BMI in the 25-29.9 range) has a four times greater risk of developing diabetes compared to a normal weight (BMI 18.5-24.9) and active person; an inactive and obese patient faces an 11 times greater risk of developing diabetes. Exercise plays a vital role in reducing a patient’s risk for diabetes; Milligan reminded the audience that even 30 minutes of exercise a day decreases risk above and beyond what is gained by weight loss.

Next, Milligan asked the audience to consider the macrovascular impact of type 2 diabetes and the key factors to consider when devising treatment plans to minimize their impact. He said simple fact is that patients with type 2 diabetes face increased coronary artery disease (CAD) morbidity and mortality. Diabetes is associated with twice the risk of CAD and stroke, and 2-4 times the risk for CND and CVA mortality. Because the data indicate that cholesterol and blood pressure lowering appear to be more effective than lowering glucose in increasing survival in patients with type 2 diabetes, it is important that physicans assess CAD risk in patients with diabetes.

Returning to the case study, Milligan provided additional information about the patient: her systolic blood pressure (BP) is 145/67, HbA1c is 7.5%, total cholesterol is 190, HDL is 36, LDL is 99, and she has 40 mcg/g microalbumin in her urine. Based on this information, Milligan reminded the audience that they can use the UKPDS Risk Engine, a “type 2 diabetes-specific risk calculator based on 53,000 patients years of data from the UK Prospective Diabetes Study,” to estimate this patient’s risk for developing diabetes. Based on the information provided, her total risk score is 13. However, Milligan said that the important point here isn’t the patient’s score per se, but rather what risk does it convey for CAD over 10 years? This patient’s 10-year risk for CAD is less than 15% according to the UKPDS (score of 0-17 gives less than 15% risk; 18-31 gives risk of 15-30%; 32-69 gives greater than 30% risk).

What if a fibrate was added to this patient’s regimen, remembering that she is already on a statin? Would it significantly reduce her risk for major cardiovascular (CV) events? Milligan said that data from the ACCORD trial and other sources show that this would in fact not reduce CV risk (but would likely increase HDL by about 10%). The ACCORD trial did not support the use of fibrate/statin combination treatment, compared with statin therapy alone, to reduce CV risk in patients with diabetes. Lipid-lowering therapy with a statin is still recommended for most patients with diabetes. Treatment reduces the risk of major CV events at any initial LDL cholesterol level, Milligan said.

Other key points to consider when evaluating patients for diabetes management:

Target LDL

The 2006 AHA/ACC secondary prevention guidelines recommend a target LDL of less than 100 mg/dL if 10-year risk of CAD is greater than 20%, with LDL of less than 70 mg/dL as an alternate goal.

Target blood pressure

The ACCORD trial found no difference in CV events in people with BP less than 130 compared to patients with BP 130-139. There is no evidence that intensive blood pressure control reduces the rate of a composite of major cardiovascular events in these patients. Reducing diastolic blood pressure to less than 80 mmHg in patients with diabetes is associated with lower rates of mortality and CV events.

Antihypertensive medications

When selecting an antihypertensive medication, remember that the evidence shows that diuretics, beta blockers, ACE inhibitors, and calcium channel blockers all appear to reduce CV mortality and morbidity in diabetic hypertensive patients. These medications have similar short-term and medium-term effects on major CV events; however, ACE inhibitors may reduce risk for MI more than calcium channel blockers in diabetics.

Frequency of home blood glucose monitoring

How often should patients check blood glucose at home? There is no evidence that supports any specific testing frequency. Optimal frequency and timing of self-monitoring of blood glucose (SMBG) for type 2 diabetics who are not on insulin is unclear; however, some SMBG regimens may be associated with lower HbA1c.

Medications for glycemic control

Most oral antidiabetic agents appear to be similarly effective for glycemic control in patients with diabetes. There is limited evidence for clinical outcomes except for a possible increased risk of CHF with glitazones. Pioglitazone and metformin are associated with reduced CV morbidity; metformin appears to be the optimal choice for first-line therapy.

Aspirin, yea or nay?

Physicians should not assume that a patient has greater CV risk just because he or she has diabetes; they must assess the patient’s actual risk for heart disease. The benefit of daily low-dose aspirin in the primary prevention of CV events or death in patients with diabetes may be lower than in other high-risk populations. Risks of bleeding might outweigh the benefits of aspirin in diabetics in certain groups.

Follow-up HbA1c testing

The consensus is that patients’ HbA1c levels should be monitored every 3-6 months; usually every three months if their HbA1c is not at goal, every six months in patients who are at goal. However, there is no evidence for or against this. Guidelines generally recommend an HbA1c goal of less than 7%, but goals should be individualized. HbA1c lower than 7% is associated with reduced mortality and diabetic complications. However, there is some data that indicates that a target HbA1c of 6-6.5% may be more harmful than beneficial; HbA1c less than 6% may actually increase mortality in some groups of diabetics.

Preventing microvascular complications

Diabetes is the leading cause of new cases of blindness, amputations, and end-stage kidney disease. The ADA recommends that all patients be screened for distal symmetric polyneuropathy at diagnosis and annually. Semmes-Weinstein monofilament testing of plantar surfaces is the preferred way to screen for diabetic neuropathy of feet. Doing the “socks off” visual inspection of feet is associated with 50% reduction in amputation rates. Patients with diabetes should have both an initial dilated and a comprehensive eye exam administered by an ophthalmologist at diagnosis or shortly after. Regular nephropathy screening is also important; all diabetic patients, starting at diagnosis, should receive an annual test to assess urine albumin excretion. Physicians should measure serum creatinine annually (at least) in all diabetic adults regardless of urine albumin excretion.

Diabetes group visits

Diabetes group visits help improve just about all vital measures and goals for patient with diabetes. Group visits improve outcomes for fasting blood glucose levels, glycated hemoglobin, patients’ diabetes knowledge, systolic bloodpressure, body weight, and diabetes medication compliance.