Starting Basal Insulin in Primary Care: A Simple, Safe Workflow for NPs

Starting insulin makes a lot of us nervous. It did for me too. The good news is that basal insulin is the simplest place to start, and a clear workflow takes most of the fear out of it. Insulin is individualized, but here's how I start it safely and confidently.

When I consider insulin

Start insulin up front, or add it, when any of these are true:

• New diagnosis with A1c ≥10%
• Severe hyperglycemia: fasting >250 mg/dL or random >300 mg/dL
• A1c >9% with ketonuria or unintentional weight loss
• Known diabetes not controlled on oral agents and/or GLP-1 therapy

Before you reach for insulin, address dehydration, infection, steroid exposure, and adherence first. Those are easy to miss and they change the picture.

First step: basal insulin

Basal insulin targets overnight and fasting hyperglycemia. It's one shot, it's predictable, and it's the easiest place to start.

Common choices, pick based on coverage:

• Insulin glargine: Basaglar, Lantus, Rezvoglar, Semglee, Toujeo
• NPH (OTC options): Humulin N, Novolin N

Glargine and NPH have a similar A1c effect. Glargine generally causes less nocturnal hypoglycemia but often costs more. If cost is the barrier, NPH is a reasonable choice used thoughtfully.

How I start the dose

There are two acceptable approaches. Pick one and stay consistent.

• Fixed start (my default): 10 units subQ at bedtime. Easy, safe, and memorable for patients and staff.
• Weight-based: 0.2 units/kg once daily. This usually lands close to 10 to 20 units.

Keep the other glucose-lowering meds the same unless there's a reason to adjust.

How I titrate: the 3 and 3 rule

Goal: fasting glucose <150 mg/dL. You can personalize to 80 to 130 if you want tighter ADA targets.

1. Start 10 units nightly.
2. Patient checks fasting glucose every morning.
3. Increase by 3 units every 3 days until fasting is at goal.

Here's what that looks like in practice:

• Mon AM 200, continue 10u Mon night
• Tue AM 190, 10u Tue night
• Wed AM 170, 10u Wed night
• Thu AM 180, increase to 13u Thu night
• Continue increases every 3 days until fasting <150

Follow up in 2 to 4 weeks, sooner if there are lows or you're titrating quickly.

When I split the dose

If the bedtime dose reaches >50 to 60 units, I often split to twice daily for smoother coverage. For example, 60u nightly becomes 30u AM + 30u PM.

Safety and counseling (copy and paste for your portal)

• Hypoglycemia plan: If glucose <70 mg/dL, use the 15-15 rule. Take 15 g fast carbs (glucose tabs or 4 oz juice), recheck in 15 min, repeat if still <70, and eat a snack if the next meal is more than an hour away.
• Driving and exercise: Check before driving or prolonged activity, and carry a glucose source.
• Sick day rules: Continue basal, hydrate, check more often, and call for persistent BG >300, ketones, vomiting, or signs of DKA.
• Injection basics: Rotate sites (abdomen, thigh, arm), use a new needle each time, and store pens per the label.
• Bedtime snacks: Not mandatory. Personalize if nocturnal lows occur.

Supplies to prescribe

• Basal insulin pen(s)
• Pen needles (e.g., 4 mm), enough to cover daily use plus extras
• Glucose meter, strips, lancets
• Hypoglycemia rescue: glucose tabs or gel, and glucagon for patients at risk of severe lows

EMR SmartPhrase (steal this)

Plan, Basal Start: Begin insulin glargine 10 units SQ nightly. Check fasting BG daily; increase by 3 units every 3 days until fasting <150 (unless BG <80 or symptomatic). Educated on injection technique, site rotation, hypoglycemia (15-15 rule), and sick-day management. Follow-up 2 to 4 weeks or sooner if lows. Consider BID split if dose >50 to 60u.

Pearls

• Glargine often means fewer nocturnal lows. NPH is cheaper and OTC, and it's fine when used thoughtfully.
• Don't wait months to adjust. Titrate weekly using home logs or portal messages.
• When fasting sugars won't budge, look for steroid bursts, missed doses, and late-night snacking.
• If fasting is normal but A1c stays high, you're seeing post-prandial hyperglycemia. That's the cue to consider adding mealtime insulin.

Frequently asked questions

What starting dose do you use for basal insulin?
My default is 10 units subQ at bedtime. If you'd rather go weight-based, use 0.2 units/kg once daily, which usually lands close to 10 to 20 units. Pick one approach and stay consistent.

How fast should I titrate?
Increase by 3 units every 3 days until fasting glucose is under 150 mg/dL, using the patient's morning fasting checks. Don't let titration stall for months. Adjust weekly off home logs or portal messages.

When should I split the basal dose?
When the bedtime dose reaches more than 50 to 60 units, split to twice daily for smoother coverage. For example, 60u nightly becomes 30u AM and 30u PM.

Is it safe to start basal insulin in primary care?
Yes, for type 2 diabetes this is squarely a primary care skill. Just screen for type 1 and DKA when the picture fits (ketones, weight loss, autoimmune history), and use your clinical judgment, local protocols, and current guidelines.

Education only, not medical advice. Use your clinical judgment, local protocols, and current guidelines. Screen for T1DM and DKA when appropriate.

Once fasting is controlled, the next move is usually adding mealtime insulin, and these insulin prescribing pearls make the scripts and supplies painless. If you want a quick at-the-visit cheat sheet that covers insulin, supplies, and CGM ordering, the Clinical Desk Reference ($37) keeps it on one page, and the Primary Care Clinical Mastery Program goes deeper if you want the full system.