Sleeve to Mini Gastric Bypass — When Insulin Resistance Won’t Budge

(Part 4 of 5 in our Revisional Operations Series: Which Surgery for Which Patient?)

For many patients, sleeve gastrectomy works beautifully: weight drops, hunger reduces, and health improves. But some people find that even after sleeve, the deeper metabolic problem — insulin resistance — still hasn’t shifted.

They lose weight, but they’re still snacking. Their HbA1c barely moves. Cravings linger. This is where revising to Mini Gastric Bypass (MGB) can make the difference.

How We Spot Persistent Insulin Resistance

Unlike reflux or anatomical problems, insulin resistance doesn’t show up on a scan. Instead, we look for:

• Ongoing cravings and grazing, especially for carbs.

• Slow or limited HbA1c improvement, even after weight loss.

• A HOMA-IR score that remains elevated.

In the UK, fasting insulin isn’t available through the NHS, which makes calculating HOMA-IR difficult. But private labs can test it, and when combined with symptoms, it’s one of the clearest markers of whether insulin resistance is still present.

Why MGB Works Better Than Sleeve Alone

Sleeve surgery mainly restricts intake and reduces ghrelin. It can help insulin resistance indirectly, but not always enough.

Mini Gastric Bypass adds another layer:

• Stronger hormonal shifts (GLP-1, GIP).

• A bigger impact on lowering fasting insulin.

• Higher rates of diabetes remission compared to sleeve.

For patients with ongoing insulin resistance, MGB doesn’t just reduce the amount they eat — it changes the way their body handles food.

Who Benefits Most

• Patients who lost weight after sleeve but still have poor metabolic control.

• Those with snacking behaviour they can’t explain.

• Patients showing high HOMA-IR scores and prediabetic HbA1c levels despite surgery.

The Bottom Line

If sleeve surgery solved the weight but left insulin resistance untouched, MGB is often the most effective second stage. It resets the metabolism where sleeve couldn’t, giving patients the chance to truly move forward.