A 51-year-old man came to us with blood sugar that would not behave. His HbA1c, the measure of average blood sugar over recent months, was 8.1 percent, and his fasting glucose was 9.2. The diagnosis was the obvious one for a man in his fifties: type 2 diabetes. He was started on metformin, the standard first treatment. When that was not enough, more oral medications were added. When those were not enough either, he was moved onto insulin. At every step his HbA1c stayed stubbornly out of control.
From the outside this looks like a patient whose diabetes was simply hard to manage, or perhaps one who was struggling to follow the plan. It happens, and it is a common story. But look at the pattern rather than the individual steps, because the pattern is the clue. He did not respond to metformin. He did not respond to combination oral therapy. He kept deteriorating despite escalating treatment, which is not the usual course of type 2 diabetes, where those medications generally work at least for a while. A patient who fails through an entire treatment ladder in sequence is often telling you that the ladder was built for a different disease.
If your diabetes keeps escalating despite treatment, and you are not overweight or do not fit the usual type 2 picture, it is worth asking whether the type of diabetes you have was ever actually confirmed with a blood test.
The reason this matters is that type 2 diabetes is diagnosed clinically, by age and circumstance and appearance, rather than by a test that proves the mechanism. Certain features suggest a different type entirely:
- A patient who is not overweight, or who has little of the usual metabolic picture
- Rapid progression through oral medications, with each one failing sooner than expected
- A relatively quick need for insulin, often within months to a few years of diagnosis
- A personal or family history of autoimmune disease, such as thyroid disease or coeliac disease
- Weight loss rather than weight gain around the time of diagnosis
- Blood sugar that behaves unpredictably, resisting the usual adjustments
None of these prove anything on their own. Together, and especially when treatment keeps failing, they point toward testing rather than escalating.
What the first opinion concluded
His first assessment came from his GP and internal medicine, which diagnosed type 2 diabetes and escalated therapy progressively, all the way to insulin.
In a 51-year-old with raised blood sugar, type 2 diabetes is by far the most likely diagnosis, and starting metformin is correct, guideline-driven care. The initial assumption was reasonable.
The problem was that the assumption was never revisited when the evidence turned against it. Each treatment failure was answered with more treatment rather than with a question about the diagnosis. And in diabetes, that question has a definitive answer available cheaply: two blood tests can distinguish the autoimmune forms from type 2. In the meantime he was on medications aimed at the wrong mechanism, including, in the usual sequence, drugs that push a pancreas to produce more insulin. If the pancreas is being destroyed rather than merely underperforming, those drugs cannot work for long, and some carry a real risk of dangerous low blood sugar while they fail.
The second opinion
He was referred for a medical second opinion to diabetology and endocrinology, and the missing tests were finally run:
- GAD antibodies, which came back positive, showing that his immune system was attacking his own insulin-producing cells
- C-peptide, a measure of how much insulin his body was still making itself, which came back low
The diagnosis was LADA, latent autoimmune diabetes in adults, sometimes called type 1.5. It is an autoimmune diabetes that begins in adulthood and progresses slowly, which is precisely why it is so often mistaken for type 2. The patient is the wrong age for classic type 1, and the onset is gradual rather than dramatic, so the label goes on and the underlying autoimmune process continues quietly underneath it.
The correction was immediate and practical. He was moved onto an appropriate insulin regimen for his actual condition, and metformin was stopped. His control became stable, and the risk of hypoglycaemia that came with sulfonylurea treatment was removed entirely. Nothing exotic was required. He simply needed the treatment that matched his disease.
Why this case matters
The lesson is direct.
The wrong type of diabetes gets the wrong treatment. LADA is systematically underestimated, particularly in patients who are not overweight.
Diabetes is often spoken about as one condition with one management plan, but the type determines the mechanism, and the mechanism determines what will work. Treating an autoimmune diabetes as a metabolic one means chasing control with drugs that were never going to deliver it, while exposing the patient to side effects for no benefit. Clear communication in healthcare means being honest that a type 2 diagnosis is usually a clinical assumption rather than a confirmed finding, and that when treatment keeps failing, confirming the type is the logical next step rather than adding another drug.
A word of balance
This is not a suggestion that type 2 diabetes is commonly misdiagnosed, because the great majority of adults with diabetes genuinely have type 2, and metformin and the standard escalation work well for most of them. LADA accounts for a minority of adult diabetes, and not every patient whose control is difficult has it. Poor control usually has more ordinary explanations. The narrow, practical point is about the combination: repeated treatment failure in a patient who does not fit the typical type 2 profile is exactly the situation where antibody and C-peptide testing belongs, because the answer changes the whole treatment plan.
A medical second opinion is especially worth seeking when:
- Your blood sugar stays uncontrolled despite escalating diabetes treatment
- You are not overweight, or you lost weight around the time you were diagnosed
- You needed insulin unusually quickly after diagnosis
- You or your family have other autoimmune conditions, such as thyroid disease
Which leaves the question this case puts plainly: when a treatment keeps failing, are we asking whether we have the right diagnosis, or simply adding the next medication in the sequence?
This is exactly the kind of case CW1 exists for, helping patients obtain a medical second opinion when treatment keeps failing, and supporting the communication in healthcare that distinguishes an assumed diagnosis from a confirmed one.
Note: this is one case rather than medical advice, and no one should change or stop diabetes medication on their own. If this resonates, the right next step is a careful conversation with a diabetes specialist.