Blood Sugar 148 mg/dl — Too High? Fasting & After Eating

A 148 on the hospital chart

In hospital, glucose is often checked several times a day, even in patients who have never had diabetes. If the nurse reads out 148, it may sound high next to the home scales you know. For most adult inpatients, though, ADA’s recommended glucose target is 140 to 180. A 148 sits at the low end of that range, which is exactly where hospital teams are usually content to keep it.

Why hospitals aim higher than everyday targets

The inpatient range is a deliberate compromise. Very high glucose slows healing and raises the risk of infection, so hospitals treat readings that stay well above 180. But very tight control is risky in hospital. Patients may be eating little, may be fasting before a procedure, may have meals delayed or vomit after eating. If insulin doses were pushed to keep everyone near 100, low blood sugar episodes would become common, and in an unwell person a low can be dangerous. A target of 140 to 180 leaves a safety margin.

Some patients, for example those after certain types of heart surgery in intensive care, may be given slightly tighter targets by their team. Frail or very sick patients may be given looser ones.

Patients can help the team. Tell staff about every diabetes or steroid medicine you take at home, including doses and timing, and say whether you usually feel lows and at what number. If you wear a CGM, ask whether the hospital allows it; many still rely on finger-sticks or lab samples for treatment decisions. And if you notice shakiness, sweating or confusion, call the nurse rather than waiting for the next scheduled check.

What pushes glucose up during an admission

• Stress hormones: surgery, injury, pain and serious infections release cortisol and adrenaline, which raise glucose. This is often called stress hyperglycemia.
• Steroids: commonly given for lung disease, swelling or inflammation, they raise glucose, especially in the afternoon and evening.
• Glucose in IV fluids or feeding: drips containing dextrose, tube feeds and nutrition through a vein all deliver sugar directly.
• Lying in bed: unused muscles take up less glucose.
• Held medicines: some diabetes tablets are paused in hospital and replaced with insulin, which is easier to adjust day by day.

After you go home

A raised glucose during an illness does not automatically mean diabetes. In many people it settles once the stress of the illness has passed. Doctors can check an A1C in hospital, which reflects the past two to three months. If it is normal, the high readings were probably caused by the illness itself. If it is in the prediabetes or diabetes range, the condition was likely there before the admission and needs follow-up.

Ask whether a repeat test is planned after discharge, and who will arrange it. Discharge papers sometimes mention “hyperglycemia” without a clear plan; your primary care doctor can pick it up. The normal blood sugar levels page summarizes everyday ranges for comparison.