A1C

Glycemic Goals in Adult with Diabetes

September 3, 2013 Diabetes No comments , , ,

Generally there are two primary techniques for health providers and patients to evaluate the effectiveness of the management plan on glycemic control: patient self-monitoring of blood glucose or interstitial glucose, and A1C. What should be emphasized is that A1C has a strong predictive value for diabetes complications.

Hyperglycemia defines diabetes, and glycemic control is fundamental to the management of diabetes. Poor controlled hyperglycemia is correlation with diabetes complications such as microvascular complications and cardiovascular diseases (CVD).

Microvascular Complications

Many studies and trials proved that the greatest number of microvascular complications would be averted by taking patients from very poor control to fair or good control. Compared with standard glycemic control (e.g., target A1C <7%), intensive glycemic control (e.g., target A1C <6.5%) seems to have more benefit on the onset or progression of microvascular complications, with further reduction in the risk of microvascular complications.

Despite these confirmed benefit of intensive glycemic control, the risks of lower glycemic targets may outweigh the potential benefits on microvascular complications on a population level when given the substantially increased risk of hypoglycemia. Thus, lower glycemic target is appropriate in selected individuals such as those with short duration of diabetes, little comorbidity, and long life expectancy, as long as significant hypoglycemia dose not become a barrier.

Cardiovascular Diseases

CVD, a more common cause of death in population with diabetes than microbascular complications, is less clearly impacted by levels of hyperglycemia or intensity of glycemic control. Studies about this topic are inconsistent.

In the DCCT, there was a trend toward lower risk of CVD events with intensive control, and in 9-year post-DCCT follow-up of the EDIC cohort participants previously randomized to the intensive arm had a significant 42% reduction in CVD outcomes and a significant 57% reduction in the risk of nonfatal myocardial infarction, stroke, or CVD death compared with those previously in the standard arm.

During the UKPDS trial, there was a 16% reduction in cardiovascular events in the intensive glycemic control arm, although this difference was not statistically significant, and there was no suggestion of benefit on other CVD outcomes such as stroke.

Conversely, results of three more-recent large trials (ACCORD, ADVANCE, and VADT) suggest no significant reduction in CVD outcomes with intensive glycemic control in these populations, who had more advanced diabetes than UKPDS participants. All three of these trials were conducted in participants with more-long-standing diabetes (mean duration 8-11 years) and either know CVD or multiple cardiovascular risk factors.

However, the benefits of intensive glycemic control on CVD primarily rests on long-term follow-up of study cohorts treated early in the course of type 1 and type 2 diabetes and subset analyses of ACCORD, ADVANCE, and VADT.

Summary

Lowering A1C to below or around 7% has been shown to reduce microvascular complications of diabetes, and if implemented soon after diagnosis of diabetes is associated with long-term reduction in microvascular disease.

Providers might reasonably suggest more stringent A1C goals (such as <6.5%) for selected individual patients, if this can be achieved without significant hypoglycemia or other adverse effects of treatment. Appropriate patients might include those with short duration of diabetes, long life expectancy, and no significant CVD.

Severe hypoglycemia should be avoid with efforts. Providers should not aggressively attempt to achieve near-normal A1C levels in patients in whom such a target cannot be reasonably easily and safely achieved (with history of severe hypoglycemia, limited life expectancy, advanced microvascular or macrovascular complications, extensive comorbid conditions, and those with longstanding diabetes in whom the general goal is difficult to attain despite DSME, appropriate glucose monitoring, and effective doses of multiple glucose-lowering agents including insulin), where a less-stringent A1C goals (e.g., <8%) might be appropriate.

Table 1 Summary of Glycemic Recommendation for Many Nonpregnant Adults With Diabetes.

The dignosis of diabetes mellitus

April 9, 2012 Diabetes No comments , , ,

There are many types of diabetes mellitus. In general there are four types of diabetes. They are type 1 diabetes, type 2 diabetes, other specific types of diabetes, and gestational diabetes.

American Diabetes Association.

Type 1 diabetes results from β-cell destruction, usually leading to absolute insulin deficiency. Type 2 diabetes results from a progressive insulin secretory defect on the background of insulin resistance. Other specific types of diabetes due to other causes, e.g. genetic defects in β-cell function, genetic defects in insulin action, diseases of the exocrine pancreas etc. And the gestational diabetes mellitus is diagnosed during pregnancy that is not clearly overt diabetes.

There also are three criterias for the diagnosis of diabetes. They are the fasting plasma glucose (FPG) [≥126 mg/dL (7.0 mmol/L)] which is defined as no caloric intake for at least 8 hours, the 2-h value in the 75-g oral glucose tolerance test (OGTT) [≥200 mg/dL (11.1 mmol/L).] which uses a glucose load containing the equivalent of 75 g anhydrous glucose dissolved in water, and the A1C test [≥6.5%].

But note that all the three criterias above should be repeated for confirmation before the diagnosis is clear, unless that the patient has classic symptoms of hyperglycemia or hyperglycemic crisis, and simultaneously his or her random plasma glucose ≥200 mg/dL (11.1 mmol/L). It is that the diagnosis of diabetes shall be clear.

A1C assay is a good way for the diagnosis of diabetes.It has many advantages compared to the FPG and OGTT, including greater convenience, evidence to suggest greater preanalytical stability, and less day-to-day perturbations during periods of stress and illness. But A1C assay is not perfect. It costs more, and the there is incomplete correlation between A1C and average glucose in certain individuals.

Also A1C inaccurately reflects glycemia with certain anemias and hemoglobinopathies. For example in conditions with abnormal red cell turnover, such as pregnancy, recent blood loss or transfusion, or some anemias, the diagnosis of diabetes must employ glucose criteria exclusively rather than A1C.

As we discussed above there are four different types mothod to diagnose diabetes and the test should be repeated to rule out laboratory error. Unless the diagnosis is clear on clinical grounds, such as a patient with a hyperglycemic crisis or classic symptoms of hyperglycemia and a random plasma glucose ≥200 mg/dL.

It is preferable that the same test be repeated for confirmation, since there will be a greater likelihood of concurrence in this case. For example, if the A1C is 7.0% and a repeat result is 6.8%, the diagnosis of diabetes is confirmed. However, if two different tests are both above the diagnostic thresholds, the diagnosis of diabetes is also confirmed. On the other hand, if two different test are available in an individual and the results are discordant, the test whose result is above the diagnostic cut point should be repeated, and the diagnosis is made on the basis of the confirmed test. That is, if a patient meets the diabetes criterion of the A1C (two results ≥6.5%) but not the FPG (≤126 mg/dL or 7.0 mmol/L), or vice versa, that person should be considered to have diabetes.

Also it is possible that when a test whose result was above the diagnostic threshold is repeated, the second value will be below the diagnostic cut point. This is least likely for A1C, somewhat more likely for FPG, and most likely for the 2-h PG. Barring a laboratory error, such patients are likely to have test results near the margins of the threshold for a diagnosis. The health care professional might opt to follow the patient closely and repeat the testing in 3-6 months.