Fasting plasma glucose concentration depends entirely on the fasting rate of hepatic glucose production and, hence, on its sensitivity to suppression by insulin. Hepatic insulin sensitivity cannot be inferred from observed postprandial change in hepatic glycogen concentration because glucose transport into the hepatocyte is not rate limiting, unlike in muscle, and hyperglycemia itself drives the process of glycogen synthesis irrespective of insulin action. Indeed, postprandial glycogen storage in liver has been shown to be moderately impaired in type 2 diabetes (50) compared with the marked impairment in skeletal muscle (51).
To this end, treatment programs such as the Cognitive Behavioural Therapy - Adherence and Depression program (CBT-AD) have been developed to target the psychological mechanisms underpinning adherence. By working on increasing motivation and challenging maladaptive illness perceptions, programs such as CBT-AD aim to enhance self-efficacy and improve diabetes-related distress and one's overall quality of life.
A useful test that has usually been done in a laboratory is the measurement of blood HbA1c levels. This is the ratio of glycated hemoglobin in relation to the total hemoglobin. Persistent raised plasma glucose levels cause the proportion of these molecules to go up. This is a test that measures the average amount of diabetic control over a period originally thought to be about 3 months (the average red blood cell lifetime), but more recently[when?] thought to be more strongly weighted to the most recent 2 to 4 weeks. In the non-diabetic, the HbA1c level ranges from 4.0–6.0%; patients with diabetes mellitus who manage to keep their HbA1c level below 6.5% are considered to have good glycemic control. The HbA1c test is not appropriate if there has been changes to diet or treatment within shorter time periods than 6 weeks or there is disturbance of red cell aging (e.g. recent bleeding or hemolytic anemia) or a hemoglobinopathy (e.g. sickle cell disease). In such cases the alternative Fructosamine test is used to indicate average control in the preceding 2 to 3 weeks.
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.