Lipodystrophy - A Cause of Brittle Diabetes
Lipodystrophy is generally characterized in the medical literature as a rare disorder of adipose (fatty) tissue resulting from a selective loss of body fat (lipoatrophy). Individuals who have the condition do not have enough fat tissue because they lack adequate amounts of leptin a hormone that helps regulate metabolism. Patients with lipodystrophy have a tendency to develop insulin resistance, severe type 2 diabetes, high triglycerides and a fatty liver.
As to the many forms of Lipodystrophy, it may be congenital (occurring at birth) or acquired (occurring later in life) or it can be generalized (affecting all of the body) or partial (limited to a region of the body. However, when the term is applied to insulin dependent diabetics,the meaning shifts. In this context, Lipodystrophy is the abnormal distribution of fat whether it be caused by lipohypertrophy (fat accumulation) or lipoatrophy (fat loss) or a combination of both.
In the case of the insulin dependent diabetic, whether stable or brittle, our focus is on subcutaneous areas of the skin within the abdominal area, the primary site for insulin injections. The skin’s subcutaneous area contains connective tissue, nerves, blood vessels and fatty (adipose) tissue. Adipose tissue is recognized to have important metabolic and endocrine roles, particularly as the principal site of two hormones, leptin and adiponectin production. In instances where this role is impacted, impaired regulation of adipose tissue blood flow has been linked to obesity and insulin resistance.
In the context of insulin use to stabilize blood glucose levels, we are looking at a rare syndrome called Acquired Partial Lipodystrophy. Insulin is a growth hormone and as a drug stimulates lipogenesis – an increase in fatty acid synthesis and triglyceride synthesis leading to the formation, deposition and storage of fatty (adipose) tissue.
According to the American Diabetes Association (ADA), in 30 percent of patients with type 1 diabetes the lipogenic effect of insulin results in subcutaneous fat deposition (lipohypertrophy) as a result of repeated insulin inoculations in and about the same area. However, in 10% of insulin dependent patients, lipoatrophy will occur when insulin is repeatedly injected into the same area. As the injected insulin is drawn away, a dent or divot occurs where adipose tissues have thinned out. This leaves the area feeling lumpy.
In each of these cases, variations in the density of fatty tissue from thin to thick occur. As you shift to a new injection site, it becomes more difficult to estimate what amount of the drug is being absorbed into the circulatory system resulting in variations in blood glucose levels. If the insulin is absorbed too quickly a hypoglycemic event may occur, if too slow, hyperglycemia may result. This unpredictable shift in blood glucose may be the cause of the brittleness being exhibited by a brittle diabetic.
There is no reversing the condition if you allow it to occur. That is why diabetes educators teach prevention of this condition when they recommend that you rotate the site of injection preventing this condition from occurring. An Infusion Site Management program (Accu-check SEE Page 29) for rotating injection sites as designed for the pump may serve to provide guidance for needle injections as well.
Treatment with metreleptin, an analog of the human hormone leptin, provided lipid control in patients with partial lipodystrophy and was found to help control BG levels in type 2 diabetics.
Inhaled insulin may be employed for individuals experiencing severe or persistent problems with injection sites.
Any patient with brittle diabetes, including those on a pump, should have their injection site checked by their physicians for this condition and rotate locations accordingly.