You might be surprised to discover that diabetes encompasses more than just two types. While Type 1 and Type 2 are well-known, you may have come across Type 1.5, which has recently gained attention.

Type 1.5 diabetes, formally known as Latent Autoimmune Diabetes (LADA), is not a new variant of diabetes but is relatively uncommon. It has been recognized as a distinct type since 1993; comprising 3 to 12 percent of all adult diabetes cases.

Nonetheless, LADA is challenging to diagnose due to its similarities with the more prevalent types, often resulting in misdiagnosis. Recent studies indicate that misdiagnosis occurs frequently, with 14% of individuals diagnosed with type 2 diabetes potentially having LADA.

Like type 1 and type 2 diabetes, LADA is characterized by elevated blood sugar levels, or glucose, in the blood.

Regardless of the diabetes type, symptoms remain consistent. These include intense thirst, frequent urination, fatigue, and unexpected weight loss. The UK’s leading charity against diabetes notes these include the “four T’s”: thirst, toileting, tiredness, and thinness. diabetes uk

If you experience these symptoms, prompt diagnosis is crucial. Left untreated, diabetes can lead to severe complications affecting the kidneys, eyes, feet, and even nerves.

So, if the symptoms are similar across diabetes types, how can healthcare experts discern which type you have? And how does this differentiation influence treatment?

Comparing Type 1.5 Diabetes to Type 1 and Type 2 Diabetes

Diabetes, in its various forms, has affected humans throughout history. Ancient healers in Greece, India, and Egypt frequently mentioned a peculiar symptom: sweet-smelling urine. Thus, the term diabetes derives from the Greek word “diabetes,” meaning to pass, and the Latin word “mellitus,” meaning sweet.

This sweet-smelling symptom arises from the buildup of glucose in the body. Glucose is processed by a hormone called insulin, produced by the pancreas, which converts it into a usable energy source for cells.

Glucose buildup occurs when the body either:

• Fails to produce sufficient insulin (as in type 1 diabetes)
• Or does not respond effectively to insulin (as seen in type 2 diabetes)

In both scenarios, the kidneys struggle to reabsorb excess glucose in the bloodstream. When they cannot eliminate glucose effectively, surplus sugar spills into the urine, indicating the presence of disease.

LADA shares numerous traits with these two predominant diabetes types, leaning closer to type 1 than type 2.

One significant reason individuals with type 1 diabetes have insufficient insulin is that their immune system attacks pancreatic cells responsible for insulin production. As these cells decline, the body struggles to maintain glucose levels.

The same is true for LADA. An influx of immune cells targets the pancreas, leading to decreased insulin production and gradually rising blood sugar levels. However, the timeline for the onset of the disease differs.

Type 1 diabetes typically has a rapid onset, often diagnosed in childhood or during a clinical emergency. In contrast, LADA progresses slowly and usually occurs in adults over 30.

As we age, a protective layer known as the periislet basement membrane (BM) develops around insulin-producing pancreatic cells. Current understanding suggests that this layer shields these cells from immune system attacks.

“By the time LADA autoimmunity begins, the pancreas [cells] have formed larger structures that provide better protection against immune attacks.” Sarah Richardson, Professor of Cellular Biomedicine, University of Exeter.

Thus, LADA’s onset resembles type 2 diabetes, which typically manifests in adults. Due to this similarity, up to 14% of individuals diagnosed with type 2 diabetes may actually have LADA.

Significance of Misdiagnosis

The primary treatment for type 2 diabetes is a medication called metformin. Administered in pill form, metformin works in two ways: it not only restricts the liver from absorbing excessive glucose but also enhances the body’s sensitivity to insulin.

However, a clear management strategy for LADA is still not established. While metformin may be prescribed, insulin replacement therapy could also be necessary. If someone has LADA misdiagnosed as type 2 diabetes, they might receive metformin when insulin is the actual requirement.

Taking inappropriate medication over extended periods can elevate blood sugar levels. Chronically high blood sugar can lead to severe complications, including heart disease, stroke, eye issues (retinopathy), foot problems (ranging from increased susceptibility to infections and ulcers to sensory loss), kidney disease (nephropathy), and nerve disorders (neuropathy).

A 2018 study published in diabetes medicine discovered that LADA patients are more likely to develop severe neuropathy compared to those with type 2 diabetes.

LADA can also invoke damage to small blood vessels, termed microvascular disease. A 2020 study indicated that strict glycemic control from the onset of LADA significantly decreases the risk of subsequent microvascular disease.

Consequently, minimizing misdiagnosis rates is vital for individuals with LADA. Fortunately, there are effective methods to distinguish LADA from type 1 and type 2 diabetes.

The first and foremost step a doctor can take is to check for antibodies. These antibodies incorrectly signal the immune system to attack insulin-producing pancreatic cells. Finding at least one antibody suggests the presence of autoimmune diabetes. Elevated antibody levels may indicate a more rapid progression of LADA.

This principle also applies when multiple antibodies are present. In such cases, immediate insulin treatment becomes crucial to help manage blood sugar levels more effectively.

Practitioners may also assess a person’s insulin output. This can be done by measuring a blood protein known as c-peptide, which is produced during insulin synthesis in the pancreas. Elevated c-peptide levels may respond well to metformin. However, if the levels are significantly low or undetectable, immediate insulin therapy should be initiated. In LADA, c-peptide levels tend to diminish over time, and it is recommended to conduct tests every six months.

A person’s body composition can further indicate LADA. Individuals exhibiting symptoms of the “four T’s” (thirst, frequent urination, fatigue, and weight loss) who maintain relatively low fat levels or body weight are generally more inclined to have LADA than type 2 diabetes. Additionally, LADA patients typically possess favorable cholesterol levels, which can aid in refining the diagnosis.

Once an accurate diagnosis is established, LADA can be treated appropriately. It’s critical to reach this point with guidance from healthcare professionals.

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