High Blood Sugar in Multiple Myeloma: What It Means

High blood sugar (hyperglycemia) can happen during multiple myeloma care, most often because of treatment side effects rather than the cancer itself. Steroids like dexamethasone and prednisone commonly used with myeloma therapies can raise blood sugar by reducing insulin effectiveness and increasing liver glucose output. ^[1] This rise is usually temporary and linked to treatment cycles, but it still deserves attention because poorly controlled glucose can increase infection risk and complicate care. ^[1]

---

Why it happens

• Steroid effects: Corticosteroids are a core part of many myeloma regimens and can cause hyperglycemia even in people without diabetes. ^[1]
• Drug interactions: Some myeloma drugs (e.g., bortezomib) may require closer glucose monitoring and adjustment of diabetes medications. ^[2]
• Overall health changes: Myeloma and its treatments can affect appetite, kidney function, and inflammation, which can make blood sugar fluctuate and harder to control. People receiving cancer therapies often need active monitoring and adjustments to avoid both high and low blood sugar. ^[3]

---

Is it dangerous?

It can be, depending on how high and how long it stays high.

• Short-term risks: Dehydration, fatigue, blurred vision, and in severe cases, diabetic ketoacidosis (DKA), which is urgent. Cancer programs often recommend holding certain treatments until glucose is brought below specific thresholds if it is very high. ^{[4] [5]}
• Infection risk: Myeloma already weakens the immune system, and high blood sugar can further impair immune responses, which is why careful control is encouraged during therapy. ^[1]
• Medication safety: Some anticancer agents note the need for dose adjustments or extra monitoring in people with diabetes, underscoring the importance of stable glucose control during treatment. ^[2]

---

When to be concerned

• Consistent readings above your target (commonly fasting >130 mg/dL or post-meal >180 mg/dL, though targets are individualized) over several days.
• Symptoms: Extreme thirst, frequent urination, nausea, confusion, fruity breath, or rapid breathing possible signs of DKA needing urgent care. Cancer care protocols advise urgent inpatient management if DKA is suspected. ^{[5] [4]}
• Before treatment days: If you use steroids on specific days (e.g., dexamethasone day), expect a spike the same day and possibly the next; plan monitoring and medication adjustments accordingly. Close monitoring during treatment is routinely recommended. ^{[6] [5]}

---

What you can do

Daily monitoring

• Check glucose more often on steroid days (e.g., before breakfast, mid‑day, and evening), and track trends. Programs recommend regular blood sugar monitoring during cancer treatment. ^{[6] [5]}
• Keep a log with timing of chemo/steroids, meals, and readings to help your team adjust plans. If you are on drugs like bortezomib, be prepared for adjustment of antidiabetic doses with close monitoring. ^[2]

Medication adjustments

• Ask about a “steroid day plan.” Some people use temporary rapid‑acting insulin or increase existing doses only on steroid days to blunt spikes. Oncology guidance supports managing hyperglycemia with glucose‑lowering medications, including insulin when needed, and sometimes pausing treatment until glucose improves if severely elevated. ^{[5] [4]}
• Review all meds with your care team, especially if you take oral diabetes drugs; dose changes may be needed with bortezomib or during steroid pulses. ^[2]

Nutrition and hydration

• Lower fast carbs (sweet drinks, juices, white bread, sweets) and favor fiber‑rich, balanced meals on steroid days; spread carbs across the day.
• Hydrate regularly unless you have fluid restrictions; dehydration worsens high glucose.

Safety with infections and kidney health

• Report fevers, cough, or wounds early, since myeloma and hyperglycemia together increase infection risk. Myeloma treatments often require assessing infection risk and kidney function as part of routine care. ^{[7] [8]}
• Kidney function matters: If kidneys are affected by myeloma proteins, glucose and medication plans may need adjustment. Clinicians commonly check kidney status in myeloma because treatment and disease can impact renal function. ^[7]

---

How your team manages this

• Proactive monitoring: Many cancer centers build glucose checks into treatment visits and for weeks to months after certain therapies. Routine blood sugar monitoring throughout treatment is advised in oncology protocols. ^{[9] [6]}
• Coordinated care: Oncology and primary care/diabetes teams collaborate to set safe targets and tailor plans. Patients on oral anticancer agents or steroids may need more frequent evaluation and medication changes to prevent complications. ^[2]

---

Key takeaways

• High blood sugar is common during myeloma therapy, especially from steroids, and is usually manageable with monitoring and timely medication/nutrition adjustments. ^[1]
• It matters because uncontrolled glucose can raise infection risk and may force treatment delays if very high. ^{[5] [4]}
• Work with your team on a steroid‑day strategy, check more often on those days, and seek urgent help if you have symptoms of severe hyperglycemia or DKA. ^{[5] [4]}

---

Frequently asked concerns

• “If I don’t have diabetes, can steroids still raise my sugar?”
  Yes steroids can cause temporary hyperglycemia even without prior diabetes, so extra checks are helpful on dosing days. ^[1]

• “Will my myeloma drugs affect my diabetes meds?”
  They can bortezomib labels note both hypo‑ and hyperglycemia in diabetics and recommend close monitoring and dose adjustments of antidiabetic agents. ^[2]

• “Can high glucose affect my treatment schedule?”
  If glucose is severely elevated, clinicians may pause or modify treatment until it is safer, and they will intensify glucose management. ^{[5] [4]}

---

Practical action list

• Track glucose more frequently on steroid days and the day after. Close monitoring during treatment is recommended. ^[6]
• Share readings with your oncology team to set a personalized target and “steroid‑day” adjustment plan. Medication adjustments are often needed to keep glucose safe. ^{[5] [4]}
• Adjust meals toward lower glycemic choices and maintain hydration.
• Watch for warning signs (nausea, confusion, deep breathing, fruity breath) and seek urgent care if present. DKA requires immediate inpatient management. ^{[5] [4]}
• Keep attention on infection prevention and early reporting of symptoms during periods of high sugar. Immune effects of myeloma and treatments make prevention important. ^[1]

---

By staying proactive, most people can keep blood sugar in a safe range throughout myeloma therapy and avoid interruptions while protecting overall health. Your care team can tailor a plan that fits your regimen, kidney function, and daily routine. ^{[7] [1]}