Lipodystrophy reactions to insulin: effects of continuous insulin infusion and new insulin analogs

Special considerations for the use of insulin in older adults

OBJECTIVE

The goal of this article is to provide guidance in prescribing insulin for older adults.

BACKGROUND

The prevalence of diabetes increases with age, with almost 30% of the elderly population diagnosed with this metabolic disorder. Along with the well-documented microvascular and microvascular complications of diabetes, older adults are at increased risk of numerous other complications, such as dementia, risk of falling, frailty, and incontinence.

DATA SYNTHESIS

Whether designing a new insulin regimen or adjusting an existing regimen, many factors must be considered; these include advantages and disadvantages of each insulin option; adverse events, particularly hypoglycemia and increased risk of falls; and comorbid conditions. When assessing insulin options for older adults, a thorough evaluation of key features, such as the pharmacokinetics and timing of administration in relation to meals, along with cost, will assist clinicians in selecting an appropriate regimen. Hypoglycemia and risk of falls are increased in older adults; tight glycemic goals must be weighed against the risk of these adverse events. The presence of comorbid conditions may interfere with older adults' ability to inject insulin and monitor their blood sugar appropriately. Specialized devices, such as insulin pens, may offer a means to assist older adults with their insulin therapy.

CONCLUSION

Prescribing insulin to older patients must be individualized and tailored to meet the needs of each individual.

Lipoatrophy induced by subcutaneous insulin infusion: ultrastructural analysis and gene expression profiling

CONTEXT AND OBJECTIVE

Subcutaneous adipose tissue (SAT) lipoatrophy (LA) is a rare complication of insulin therapy. We aimed to analyze the ultrastructural and molecular aspects of LA lesions.

SETTING AND PATIENTS

Macroscopic and microscopic morphology of SAT beneath the LA areas from patients with type 1 diabetes treated with Lispro insulin by continuous sc insulin infusion was studied using magnetic resonance imaging, immunohistochemistry, electron microscopy, and quantitative PCR for adipose tissue-specific genes.

RESULTS

SAT was present in LA lesions characterized by: 1) smaller, unilocular perilipin-positive adipocytes, with lipofuscin granules; 2) some "slimmed cells" losing lipid droplets as those we observed during starvation; and 3) numerous perivascular preadipocytes. We did not identify inflammatory cells. SAT in LA areas displayed a strong leptin down-regulation and an increase of AEBP1, a preadipocyte marker.

CONCLUSIONS

Our results clearly indicate that the remarkable reduction in fat cell lipid droplets and adipocyte size justifies the decrease of SAT without a reduction in adipocyte number because of necrosis or apoptosis. Thus, immune cells and any other toxic damaging fat cells were not involved in the generation of LA. We speculate that adipocytes chronically exposed to high local insulin concentrations could become severely insulin resistant, dramatically increasing lipolysis and giving rise to "slimmed cells." Clinical LA regression could be explained by the active recruitment of preadipocytes, even if they were unable to differentiate and regenerate adipose tissue unless the insulin injection was removed.

Insulin absorption from lipodystrophic areas: a (neglected) source of trouble for insulin therapy?

The experienced clinical diabetologist first checks the skin at the area where the patient usually injects his insulin when he sees widely fluctuating blood glucose levels in the diary of the patient. He knows that insulin absorption from skin with lipodystrophic changes is irregular. However, our scientific knowledge about why this is the case is very limited. Most probably, the number of blood vessels near the insulin depot in the subcutaneous tissue varies depending on the nature of the lipodystrophic changes, or the structural changes in this tissue hamper the diffusion of insulin. Not only is our knowledge about the number of patients who exhibit such changes very limited, but also our understanding why such changes show up in certain patients and not in others is minimal. More practically important, we also have few quantitative studies investigating the impact of this diabetes-related complication on insulin absorption/insulin action; however, it is not difficult to run such studies in practice. Nevertheless, it is impressive to see how often metabolic control improves considerably once the patients apply the insulin into other skin areas.

Circulating insulin antibodies: influence of continuous subcutaneous or intraperitoneal insulin infusion, and impact on glucose control

The purification of animal insulin preparations and the use of human recombinant insulin have markedly reduced the incidence, but not completely suppressed, the development of anti-insulin antibodies (IAs). Advances in technologies concerning the mode of delivery of insulin, i.e. continuous subcutaneous insulin infusion (CSII), continuous peritoneal insulin infusion (CPII) and more recently inhaled insulin administration, appear to significantly increase circulating levels of immunoglobulin G (IgG) anti-IAs in diabetic patients. However, the increase is usually moderate and mostly transient as compared to previous observations with poorly purified animal insulin preparations. The clinical impact of these circulating anti-IAs remains unclear. Nevertheless, several studies have suggested that antibodies could retard insulin action, leading to a worsening of postprandial hyperglycaemia and/or serve as a carrier, thus leading to unexpected hypoglycaemia. CPII may be associated with more marked and sustained increase in IAs levels, possibly related to the use of an unstable insulin and the formation of immunogenic aggregates of insulin. The possible clinical consequences of these high levels of IAs remain to be evaluated because a low-glucose morning syndrome or severe insulin resistance with ketone bodies production have been reported in some cases. In conclusion, even if CSII and CPII may promote the development of circulating IAs, this increase does not lead to immunological insulin resistance, compared to that previously described with animal non-purified insulin preparations, and seems to have only marginal influence on blood glucose control or complications in most diabetic patients.

A review of the management of implanted medical devices for diabetes: trends and directions

The management of diabetes is progressing rapidly from the use of traditional finger sticks for glucose monitoring and multiple daily injections of insulin to more user-friendly devices and approaches. These advances hold the promise of freeing persons with diabetes from the need for continued daily compliance, thereby improving their quality of life and improving control of their underlying diabetes. An underlying theme to solutions based on percutaneous or fully implanted devices is that the useful lifetime of such devices is often limited by the body's foreign body response. This review briefly outlines general factors associated with point-in-time needle stick approaches to the growing use of short-term percutaneous implants (< or =7 days) to the challenges of more extended devices, both technical and regulatory, faced by developers of these devices.