Individualizing Treatment of Hyperglycemia in Type 2 Diabetes
GLP-1 receptor agonists have recently received much attention for their potential beneficial effects on cardiovascular outcomes. In a recent trial, lixisenatide was shown to be safe in patients with T2DM and acute coronary syndrome when compared to placebo [82]. More recently, the Liraglutide Effect and Action in Diabetes: Evaluation of cardiovascular outcome Results (LEADER) trial demonstrated significant cardiovascular benefits with liraglutide in patients with T2DM and established or high CVD risk [83]. The composite outcome of the first occurrence of death from cardiovascular causes, nonfatal myocardial infarction (MI), or nonfatal stroke, occurred less frequently in the liraglutide group compared to placebo (13% versus 14.9%, respectively), and there were fewer deaths from cardiovascular causes in the liraglutide group compared to placebo (4.7% and 6.0%, respectively) [83]. Other trials investigating the cardiovascular outcomes of this class [84,85] are in progress.
Another class with potential cardiovascular benefits is the SGLT-2 inhibitors. In a recent cardiovascular outcome study, empagliflozin significantly lowered the composite of cardiovascular death, nonfatal MI, or nonfatal stroke in T2DM patients with high cardiovascular risk compared to placebo (10.5% and 12.1%, respectively) [86]. There are several large ongoing studies evaluating the cardiovascular effects of other SGLT-2 inhibitors [87–89].
DPP-4 inhibitors were examined in recent studies and have shown no cardiovascular benefits [42,44,90].The studies showed mixed results regarding an association between DPP-4 inhibitors and heart failure. In one study, saxagliptin was associated with increased hospitalization for heart failure compared to placebo [44], while 2 noninferiority trials did not show a significant increase in heart failure hospitalizations associated with alogliptin and sitagliptin when compared to placebo [42,90].
Administration Considerations
Many patients with T2DM require multiple agents for glycemic control. Additional medications used for comorbid conditions add to this burden. When choosing antihyperglycemic agents, the route and frequency of administration, as well as the patients’ preferences and ability, should be considered. Either once or twice daily dosing is available for most agents, and once weekly dosing is available for some of the GLP-1 receptor agonists. Once daily or once weekly formulations may improve adherence and be more desirable than preparations that are dosed twice daily. Most of the commonly used medications are dosed orally. Although many patients find this route of administration preferable to insulin or GLP-1 receptor agonists, which require injections, some patients may prefer the risk/benefit of injectable agents. All GLP-1 receptor agonists come in a pen delivery system, which eliminates mixing and provides more convenient administration. Extended-release exenatide also is available as a single-dose tray that requires mixing and may be more cumbersome to inject.
Insulin requires special consideration. There has been an enormous increase in the number of insulin products on the market in the past 2 decades. These products include insulin analogs, concentrated insulins (U-200, U-300, and U-500), premixed insulin preparations, and ultra-long-acting insulin [91]. The availability of insulin options with different concentrations, onsets, and durations of actions has made decision making on which insulin to use difficult. Clinicians need to consider patient preference, dosing frequency, and timing with regard to meals, insulin dose, administration, as well as cost. For example, concentrated insulin is preferred for a patient on high doses of insulin requiring injecting a large volume of insulin. Rapid-acting insulin analogs would be more appropriate for patients who have difficulty administering their regular insulin 20 to 30 minutes before eating. Premixed insulin preparations make it impossible to independently adjust short- and long-acting components. However, these may be good choices in patients who have consistent meal schedules and who want to simplify administration. Despite a prevailing misconception that NPH must be given twice a day, it has long been recognized that in T2DM, a single daily injection of NPH yields improvements in control similar to those achieved with 2 daily injections [92].
Cost Considerations
Treating T2DM imposes a great financial burden on individuals living with diabetes and their families due to the high cost of the medications. Table 4 and Table 5 provide information on the cost of non-insulin and insulin diabetes medications for patients who do not have prescription insurance coverage. From a practical standpoint, choice of diabetes agents is largely influenced by insurance formularies.
The older agents, metformin and the sulfonylureas, are available for a cash (no insurance) price of as little as $4 per month. This is in stark contrast to the SGLT-2 inhibitors, GLP-1 receptor agonists, and DPP-4 inhibitors, which range in cost between $400 and $600 per month. Of recent concern, the cost of insulin has been skyrocketing, with a more than 500% increase in the cost of certain insulins from 2001 to 2015 [93]. According to the Medical Expenditure Panel Survey (MEPS) from 2002 to 2013, the mean price of insulin increased by about 200% (from $4.34/mL to $12.92/mL) during this period, which was significantly higher than increases in the price of non-insulin comparators [94]. The introduction of biosimilar insulins to the market is expected to offer treatment options with lower cost. This will be tested when the biosimilar glargine, the first FDA-approved biosimilar insulin, becomes available in the U.S. market. However, a significant reduction in insulin prices is not expected soon [95].
When insulin is required, most patients with T2DM can be treated with older human insulins, which have similar efficacy and lower costs than the more expensive newer insulin analogs. A Cochrane review comparing basal insulin analogs to NPH showed similar efficacy in glycemic control with minimal clinical benefit in the form of less nocturnal hypoglycemia in the insulin analog arm [96]. Furthermore, similar glycemic control and risk of hypoglycemia was seen when regular insulin was compared with the rapid-acting insulin analogs [97]. The cost of human NPH insulin for a patient on a total daily dose of 60 units is approximately $52 per month. This contrasts with the most widely used insulin, insulin glargine, which has a cash price of about $500 per month for the same amount (Table 5). Insulin pens, which are convenient, are more expensive. Interestingly, human insulins do not require prescriptions, allowing underinsured, underfunded patients ongoing access to them.
Incorporating Patient Preferences
Research evidence is necessary but insufficient for making patient care decisions. Along with the potential benefits, harms, costs, and inconveniences of the management options, patient perspectives, beliefs, expectations, and health-related goals must be considered. Patients will undoubtedly have preferences regarding defining goals and ranking options. Clinicians should discuss therapeutic goals and treatment options and work collaboratively with patients in determining management strategies [98].
Summary
Potential treatment approaches for treating hyperglycemia in T2DM are summarized in Figure 1 and Figure 2 [4,7]. As long as there are no contraindications, metformin should be recommended concurrent with lifestyle intervention at the time of diabetes diagnosis. Even if metformin monotherapy is initially effective, glycemic control is likely to deteriorate over time due to progressive loss of β-cell function in T2DM.
There is no consensus as to what the second-line agent should be. Selection of a second agent should be made based on potential advantages and disadvantages of each agent for any given patient. A patient-centered approach is preferred over a fixed algorithm. If the patient progresses to the point where dual therapy does not provide adequate control, either a third non-insulin agent or insulin can be added. In patients with modestly elevated A1C (below ~8%), addition of a third non-insulin agent may be equally effective as (but more expensive than) addition of insulin.
Patients with significantly elevated A1C levels on non-insulin agents usually should have insulin added to their regimen. When insulin is added, metformin should be continued. DPP-4 inhibitors and sulfonylureas are typically stopped. If SGLT-2 inhibitors and/or GLP-1 receptor agonists are continued, this may aid with weight maintenance. However, continuing these agents is likely to be expensive and associated with problems associated with polypharmacy.
The most widely recommended strategy for initiating insulin in T2DM is to add a single bedtime injection of basal insulin (ie, NPH, glargine, detemir, or degludec) to the patient’s regimen. This regimen has been found to be effective in numerous studies and controls hyperglycemia in up to 60% of patients [99]. If the patient is treated with a single bedtime injection of insulin and the fasting glucose level is within the target range but the A1C level remains above goal, addition of mealtime insulin injections is likely to be beneficial. Alternatively, addition of a GLP-1 receptor agonist to basal insulin has been shown to be equally beneficial [4,6]. When adding mealtime insulin, a common strategy is to add a single injection of a rapid-acting insulin (eg, lispro, aspart, glulisine) before the patient’s largest meal of the day. Additional premeal injections of rapid-acting insulin may be added as needed, based on self-monitoring blood glucose results. If glycemia remains significantly uncontrolled on more than 200 units of insulin per day, switching to a concentrated form of insulin (eg, U-200, U-300, or U-500) should be considered.
Corresponding author: Maryam Fazel, PharmD, BCPS, BCACP, CDE, 1295 N. Martin Ave. (Room B211B), Tucson, Arizona 85721-0202, maryamfazel@pharmacy.arizona.edu.
Financial disclosures: None.
