Blood Glucose Management for Type 2 Diabetes Reviewed

Laurie Barclay, MD

January 12, 2009

To earn CME related to this news article, click here.

January 12, 2009 — Recommendations for managing blood glucose levels for type 2 diabetes mellitus are provided in a review published in the January 1 issue of American Family Physician. The vital importance of this topic is underlined by the following facts:

  • In the United States, type 2 diabetes is the sixth leading cause of death, directly causing more than 73,000 deaths annually and contributing to more than 220,000 deaths.

  • In adults, type 2 diabetes is the leading cause of renal failure and new cases of blindness, and the disease is an important cause of lost workforce productivity.

  • Of more than 20 million people in the United States with type 2 diabetes, 6 million do not have a diagnosis.

  • Type 2 diabetes disproportionately affects ethnic and racial minorities.

"Derangement of glucose homeostasis and the eventual development of diabetes is a multifactorial process involving genetics, ethnic and racial heritage, and environmental factors," write Cynthia M. Ripsin, MD, MS, MPH, from the University of Texas Medical Branch in Galveston, and colleagues. "Although the precise interplay of these factors is not yet fully understood, long-term trials have provided evidence to support aggressive efforts to prevent and manage this disease."

Although the American Diabetes Association recommends a hemoglobin A1c (HbA1c) goal of less than 7% and maintaining blood glucose levels as close to normal as possible without causing hypoglycemia, algorithms for achieving blood glucose control are based on expert consensus opinion and have not been validated by clinical trials.

Three strategies highlighted by evidence-based guidelines for the treatment of type 2 diabetes include intensive lifestyle intervention; aggressive management of cardiovascular risk factors; and normalization of blood glucose levels, with target HbA1c level less than 7%.

Recommended lifestyle interventions include incorporating 150 minutes per week or more of physical activity; a low-fat, reduced-energy diet; and weight loss with an initial goal of 7% of baseline weight, which has been shown to lower the incidence of type 2 diabetes by 58%. The review authors estimate that 6.9 persons would need to undergo intensive lifestyle intervention to prevent 1 new case of type 2 diabetes in 3 years. Exercise and weight loss may reduce triglyceride levels and visceral adiposity and lower HbA1c levels by 0.6%.

To lower cardiovascular risk and improve survival, multifactorial interventions are recommended.

Cardiovascular risk factors such as hypertension, dyslipidemia, and microalbuminuria should be aggressively managed with aspirin, statins, and angiotensin-converting enzyme inhibitors.

Daily low-dose aspirin is recommended for patients older than 40 years with type 2 diabetes or for those who have additional risk factors for cardiovascular disease (CVD). Patients with type 2 diabetes and CVD, or who are older than 40 years with type 2 diabetes and have 1 other CVD risk factor, should take statins.

The hallmarks of type 2 diabetes are insulin resistance, reduced insulin secretion, and increased hepatic glucose output. Each class of available diabetes medications targets 1 or more of these characteristics.

Compared with lifestyle intervention alone or placebo, monotherapy with any hypoglycemic agent more effectively decreases HbA1c levels, with absolute reductions ranging from 0.5% to 1.0% for exenatide, pramlintide, and alpha-glucosidase inhibitors to 1% to 2.5% for sulfonylureas and metformin. However, short-term glucose control may not be indicative of longer-term outcomes, and not all hypoglycemic agents have been shownto decrease morbidity and mortality rates.

Metformin, a biguanide, is considered a first-line agent and has been shown to reduce progression from glucose intolerance to type 2 diabetes and to reduce mortality rates in patients with type 2 diabetes. The mechanisms of action of metformin are to decrease hepatic glucose output and sensitize peripheral tissues to insulin. To prevent 1 case of type 2 diabetes, the number needed to treat with metformin is 13.9.

Other medications include sulfonylureas and nonsulfonylurea secretagogues, alpha-glucosidase inhibitors, and thiazolidinediones. Sulfonylureas and other secretogogues can cause weight gain, and although they increase insulin secretion, they lack sufficient evidence of benefit for cardiovascular outcomes.

In patients newly diagnosed with type 2 diabetes, insulin can be used acutely to normalize blood glucose levels. It may also be added to treatment with oral agents for better glycemic control if fasting blood glucose levels are consistently greater than 250 mg/dL or if random glucose level is greater than 300 mg/dL. Because of potential teratogenicity with oral medications, insulin is the agent of choice for all pregnant women with type 2 diabetes.

Although home monitoring can be used to adjust medication doses between measurements of HbA1c levels, it is expensive and time consuming. Especially in relatively well-controlled patients, home monitoring of blood glucose levels is of questionable value except for patients taking multiple insulin injections. Home monitoring should be used as indicated based on individual patient needs because there are no evidence-based recommendations regarding the optimal frequency of home glucose monitoring.

Specific key clinical recommendations, and their accompanying level of evidence rating, are as follows:

  • Patients with impaired glucose tolerance should receive counseling and education regarding weight loss and physical activity (level of evidence, A).

  • In patients with type 2 diabetes, the only medication proven to reduce mortality rates is metformin (level of evidence, A).

  • Acarbose appears to be associated with a lower risk for CVD events (level of evidence, B).

  • Oral agents should be continued initially when insulin is added to a regimen of oral medication. Long-acting insulin should be used at first, with initial dosage usually 10 units/day or 0.17 to 0.5 units/kg/day, and it should be titrated in increments of 2 units approximately every 3 days (level of evidence, C).

The review authors have disclosed no relevant financial relationships.

Am Fam Physician. 2009;79:29-36.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.