**11. Lipohypertrophy**

LH is the most common complication of insulin injection [59–62] or infusion [63, 64], with prevalence rates of 50% or higher. Risk factors for LH appear to be longer time on insulin, more daily injections, failure to carefully rotate injection sites, and extensive reuse of needles [59, 65–68]. The latter two risk factors are modifiable. Insulin injected into LH has been reported to have delayed or erratic absorption which may worsen glucose control, although these trials are older with less rigor, less precise insulin assays, or very small sample sizes which in one case led to a conclusion that injecting into LH did not worsen inherent variability of insulin uptake [69–72]. A crossover glucose clamp study [73] showed that both insulin absorption and action when injected into LH are blunted and are 3–5X more variable than when the same insulin dose is injected into non-LH areas. A controlled mixed-meal tolerance test in the same study also showed a reduced insulin absorption, and prolonged postprandial hyperglycemia when the insulin was injected into the LH area. When patients change from delivering insulin into LH and move to normal tissue, they are at risk of hypoglycemia and must lower their doses. Gentile [74, 75] has shown convincingly that HCPs trained to detect LH can do so with extremely high efficiency using the physical examination alone, achieving up to 97% consistency levels. FITTER issued the following recommendations:

An interventional study in Moscow [80] followed three groups of T1DM and T2DM patients for 6 months. Two groups received structured injection training (with one group receiving 4-mm needles for each injection while the other did not) and a control group which did not get training or needles. Both training groups had HbA1C reductions of approximately 1% but the non-training group saw no change. Needle reuse and LH declined in the training groups and injection technique improved but none of these changes were seen in the non-training

Optimal Insulin Delivery

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The available data from intervention trials in patients with insulin-related LH show consistently positive outcomes. However, there are limitations to each trial—some were not randomized; in another, the control group received meaningful parts of the educational intervention [79]. Results of one or more ongoing randomized clinical trials should provide more definitive

Reusing needles is a common practice of injecting patients, mainly for reasons of convenience and cost-saving. However, a number of studies have linked needle reuse to LH [59, 65, 66, 81–83], especially when the reuse is excessive (≥5 times/needle). Injection pain was associated with reuse in one study [84] although another one disputed these results [85]. Another study found bacterial growth on reused needles and inflammatory changes (skin redness) at injection sites of patients who reused needles [86, 87]. Although local infections or abscesses have not been reported with needle reuse, FITTER recommends against reusing needles, which are

Patients should never share insulin pens, whether in the hospital or at home setting. Blood can be aspirated back into the pen cartridge even after one injection, and this could possibly transmit a blood-borne disease such as HIV or hepatitis to the next user. Sonoki [88] found hemoglobin in a number of cartridges which patients had used only once. Le Floch [89] also studied the contamination of cartridges after one use and found similar findings. A recent US study corroborated these findings [90]. The rule with insulin injections is clear: one patient/

Insulin needles are the most commonly used sharp worldwide. If not disposed of properly, needle-stick injuries with used insulin needles could transmit hepatitis, HIV, or other bloodborne pathogens. This is a major public health issue. Technologies exist to minimize this risk. FITTER recommended the following to minimize the risk of needle-stick injuries, particularly

answers to the impact of injection technique training in the near future.

group.

**12. Needle reuse**

**13. Safety**

one insulin pen.

labeled by regulatory agencies for single use.

in a hospital or other inpatient setting:


A multicenter interventional study in the UK [78] showed that education focused on these recommendations resulted in significantly reduced clinically detectable LH after 6 months, with LH either disappearing completely or decreasing by approximately 50% from its original size. The mean HbA1c fell by more than 4 mmol/L, and there were significantly reduced levels of unexpected hypoglycemia and glycemic variability. The mean TDD of insulin in the study population fell by an average of 5.6 IU by study close.

In a controlled, prospective, multicenter study in French patients [79], all of whom had LH, the intervention consisted of instructions to move injections to non-LH areas, to correctly rotate within injection sites, to forego needle reuse, and to switch to 4-mm needles in order to facilitate correct rotation without increased IM injections. These patients were also given intensive education on the injection recommendations as summarized in this chapter. Control patients were informed of the presence of LH and were told that injections should not be given into LH. They received usual and standard education. In the intervention group, there was a significant decrease of TDD of insulin of approximately 5 IU versus baseline (P = 0.035). There were significant decreases in HbA1c (up to 0.5%) in both intervention and control groups, with no significant differences between groups. A significant number of intervention patients improved their IT habits. The authors concluded that the intervention was effective in both groups, but that intensive education in LH management yielded more rapid and superior outcomes.

An interventional study in Moscow [80] followed three groups of T1DM and T2DM patients for 6 months. Two groups received structured injection training (with one group receiving 4-mm needles for each injection while the other did not) and a control group which did not get training or needles. Both training groups had HbA1C reductions of approximately 1% but the non-training group saw no change. Needle reuse and LH declined in the training groups and injection technique improved but none of these changes were seen in the non-training group.

The available data from intervention trials in patients with insulin-related LH show consistently positive outcomes. However, there are limitations to each trial—some were not randomized; in another, the control group received meaningful parts of the educational intervention [79]. Results of one or more ongoing randomized clinical trials should provide more definitive answers to the impact of injection technique training in the near future.
