Inpatient hyperglycemia management: A practical review for primary medical and surgical teams

SPECIFIC SITUATIONS AND POPULATIONS

Type 1 diabetes

Patients with type 1 diabetes have minimal to absent pancreatic beta cell function and rely on the exogenous administration of insulin to maintain glucose homeostasis. They have worse glycemic control and higher rates of acute kidney injury than patients with type 2 diabetes; however, the impact of inpatient glycemic control on clinical outcomes has not been determined in patients with type 1 diabetes. Insulin therapy must provide both basal and nutritional components to achieve the target goals. It is important to ask the patient directly to determine the times and doses of prescribed insulin, medication adherence, recent dietary habits (including changes in appetite), and level of physical activity. This information will be used to guide insulin therapy.

A systematic review of 16 clinical studies reported that patients who possess excellent self-management skills can be suitable for successful inpatient diabetes self-management.³⁸ The American Diabetes Association supports patient self-management of diabetes in the hospital.³⁹ However, the competence and readiness of each patient with type 1 diabetes need to be carefully determined in an individualized manner. Potential candidates for inpatient self-management are those with unaltered mental status, proven proficient outpatient skills (eg, carbohydrate counting, frequent glucose monitoring, strong knowledge related to the management of insulin pump or injection techniques), and who are tolerating oral intake.

Enteral nutrition and tube feeding

Accidental dislodgement of feeding tubes, temporary discontinuation of nutrition due to nausea or for diagnostic testing, and cycling of enteral nutrition with oral intake in patients with an inconsistent appetite pose unique challenges in the hospital. Although it may be tempting to give basal and nutritional requirements to these patients as a single dose of long-acting insulin, this is not recommended. Low-dose basal insulin plus scheduled doses of short-acting (regular) insulin (every 6 hours) or rapid-acting insulin (every 4 hours) with correction insulin is often used. Some providers prefer giving intermediate-acting (NPH) plus short-acting (regular) insulin every 8 hours or every 12 hours.

It is generally accepted that diabetic enteral formulas that are low in carbohydrate and high in monounsaturated fatty acids are preferable to standard high-carbohydrate formulas in hospitalized patients with diabetes. In a meta-analysis, the postprandial rise in glucose was reduced by 20 to 30 mg/dL with the low-carbohydrate high-fat formulations compared with standard formulations.⁴⁰

Parenteral nutrition

The use of parenteral nutrition has been linked to aggravation of hyperglycemia independent of a history of diabetes as well as a higher risk of complications, infections, sepsis, and death.⁴¹ Regular insulin can be added to the parenteral solution at a starting dose of 0.1 U/g of dextrose in nondiabetic patients and at 0.15 U/g of dextrose in patients with diabetes.⁴²

Alternatively, insulin can be given as a continuous IV infusion. Hemodynamically stable patients with mild to moderate hyperglycemia can be managed with basal insulin plus scheduled or as-needed doses of short-acting (regular) insulin every 6 hours. To prevent waste, it is better to underestimate the insulin added to parenteral nutrition so as to avoid having to discontinue it prematurely or add additional glucose.

Glucocorticoids

Glucocorticoids typically raise glucose starting 4 to 6 hours after administration. Low doses of glucocorticoids given in the morning tend to raise the late morning to evening glucose levels without affecting the fasting glucose. In this situation, the patient may be managed on prandial insulin without long-acting basal insulin or with intermediate-acting insulin given in the morning. Higher glucocorticoid doses may raise fasting glucose levels, in which case basal-bolus insulin would be appropriate, with the basal component comprising about 30% and the bolus about 70% of the daily dose.²⁶

Insulin pump

Approximately 400,000 US patients with diabetes use an insulin pump.⁴³ Successful management of inpatient diabetes with the continuation of insulin pump therapy has been previously demonstrated in select patients. Clear hospital policies, procedures, and physicians’ orders with specifics on the type of diet, frequency of point-of-care glucose testing, and insulin doses (ie, basal rates, carbohydrate ratios, and correction formulas) should be in place. An inpatient diabetes specialist should assist with the assessment and management of a patient with an insulin pump.

If pump use is contraindicated (Table 4)⁴⁴ or if inpatient diabetes resources are not available, discontinuation of insulin pump and transition to a basal-bolus insulin regimen (“pump holiday”) may be the safest and most appropriate step. Most patients knowledgeable in insulin pump therapy are able to display in their pump screen the average total daily insulin used for the past few days. Based on this, safe estimations of basal, bolus, and supplemental insulin can be calculated. To avoid severe hyperglycemia or ketoacidosis from lack of basal insulin, it is important to administer the basal insulin component at least 2 hours before disconnecting the insulin pump.

Concentrated insulins

U-500 regular insulin is concentrated insulin that delivers the same amount of units in one-fifth the volume of conventional insulins, which are U-100. Whereas there are 100 units of insulin in 1 mL for conventional insulins, there are 500 units of U-500 regular insulin in 1 mL. Its onset of action is similar to that of regular insulin, and the peak and duration are similar to that of NPH insulin. Concentrated insulin is often administered in the outpatient setting to patients who are insulin resistant and require close to 200 units a day. The U-500 pen device was approved in January 2016 and was projected to be available in April 2016. For now, it can only be procured in the vial form. This causes confusion in its dosing since it is given either with the usual insulin syringes, which are designed for U-100 insulin administration, or a tuberculin syringe, which is not marked in units but in milliliters.

Because of its unique nature and providers’ lack of familiarity with U-500, certain institutions have a policy for its use. In many institutions, the doses are confirmed by pharmacy staff and delivered by pharmacy to the patient’s medication bin predrawn in a tuberculin syringe.⁴⁵ In addition, a study reported that many patients on U-500 at home required significantly lower doses of insulin (average dose of 100 U/day) while hospitalized patients could be managed with conventional insulin formulations.⁴⁵

There are newer concentrated insulins in the market, such as insulin glargine 300 U/mL (Toujeo) and insulin lispro 200 U/mL (Humalog). These insulins, so far, come only in the pen device form and not in vials, obviating the need for dose calculations using a U-100 insulin syringe or tuberculin syringe. The efficacy and safety of these insulin formulations have not been determined in the hospital setting.

Transitioning from home to hospital

Transition to an outpatient setting requires planning and coordination. Although insulin is used in the hospital for most patients with diabetes, many patients do not require insulin after discharge. On the other hand, diabetes regimens sometimes need intensification in other patients. One study showed that patients with acceptable diabetes control (HbA1c < 7.5%) near or on admission could be discharged on their prehospitalization treatment regimen, while those with HbA1c between 7.5% and 9% could be discharged on oral agents plus basal insulin at 50% of the hospital basal dose.⁴⁶ Additionally, patients with an HbA1c of 9% to 10% should be discharged on a basal-bolus regimen or on a combination of oral agents plus basal insulin at 80% of hospital dose, with a reduction in HbA1c seen 12 weeks after discharge.

SUMMARY

Inpatient hyperglycemia is common and is associated with increased risk of hospital complications, higher healthcare resource utilization, and higher rates of in-hospital mortality. In the critically ill, IV insulin is most appropriate, with a starting threshold no higher than 180 mg/dL. Once IV insulin is started, the glucose level should be maintained between 140 and 180 mg/dL.

In noncritically ill patients, a basal-bolus regimen with basal, prandial, and correction components is preferred for patients with good nutritional intake. In contrast, a single dose of long-acting insulin plus correction insulin is preferred for patients with poor or no oral intake. Preliminary data indicate that incretin therapy has the potential to improve glycemic control in patients with mild to moderate hyperglycemia and a low risk of hypoglycemia.

Transition to an outpatient setting requires planning and coordination. Measuring HbA1c at admission is important to assess preadmission glycemic control and to tailor the treatment regimen at discharge. Patients with acceptable diabetes control could be discharged on their prehospitalization treatment regimen. Patients with suboptimal control should have more intensified therapy.

Dr. Umpierrez is supported in part by research grants from the American Diabetes Association (1-14-LLY-36), PHS grant UL1 RR025008 from the Clinical Translational Science Award Program (M01 RR-00039), and grants from the National Institutes of Health and the National Center for Research Resources. He has received unrestricted research support for inpatient studies (at Emory University) from Sanofi, Merck, Novo Nordisk, and Boehringer Ingelheim, and has received consulting fees and/or honoraria for membership on advisory boards from Novo Nordisk, Sanofi, Merck, Boehringer Ingelheim, and Regeneron.