Feasibility and outcomes of insulin therapy in elderly patients with diabetes mellitus

The use of insulin in elderly patients raises special considerations. Most people who develop diabetes mellitus late in life have type 2 diabetes mell itus, in which there is some residual endogenous insulin secretion. This pa ncreatic insulin secretion, when present, stabilises their metabolic status . However, some elderly people lose virtually all their endogenous insulin secretory capacity over time, or may even have type 1 (autoimmune) diabetes mellitus with no endogenous insulin. Generally, older patients with diabet es mellitus can be managed for years, often decades, with nutritional thera py and oral agents. More options exist now than did previously. In addition to a variety of sulfonylureas, there is metformin, troglitazone, and/or al pha-glucosidase inhibitors, that are viable options to be used before turni ng to insulin. The goals of insulin therapy in the elderly must be considered. When hyperg lycaemia causes symptoms (polyuria, polydypsia and bodyweight loss) blood g lucose levels are generally >200 mg/dl, and insulin is needed if maximal do ses of oral agents have been used. Insulin is also indicated when hyperglyc aemia puts patients at risk of hyperosmolar states, for example, when blood glucose is >300 mg/dl during a normal day. Clinical judgement dictates whe ther to use insulin to control glycaemia in the attempt to avoid long term complications such as neuropathy, retinopathy or nephropathy. Ln people wit h relatively short life expectancy, major comorbities and no sign of diabet ic complications, the risk may be small. On the other hand, in patients for whom neuropathy, in particular, is a major risk, controlling glycaemia (wi th insulin if necessary) does reduce that risk. Most patients with type 2 diabetes mellitus can be managed with relatively simple insulin regimens thanks to their endogenous insulin secretion. A sin gle bedtime dose of neutral protamine Hagedorn (NPH) insulin, with or witho ut continuation of daytime oral agents, may control fasting blood glucose. A pre-mix combination of NPH and Regular insulin such as 70/30 or 50/50 may be used pre-meal. More customised, 'intensive' insulin regimens are needed when the glycaemia is unstable. Hypoglycaemia is clearly the most significant risk of insulin therapy. Lf m ild and easily treated, it is of no real concern. On the other hand, noctur nal hypoglycaemia, and, in particular, hypoglycaemia unawareness, are clear signs that the insulin regimen should be modified. In summary, insulin therapy may be necessary, and can be used effectively, in elderly patients. However, risk:benefit considerations must be taken int o account when deciding which patients to treat with insulin and what insul in regimen to use.