Flatbush Diabetes: The Overlooked Form of Diabetes Impacting Black Communities

Diabetes is often framed as either Type 1 or Type 2. But for many patients—particularly in Black communities—that binary framework misses an important and potentially dangerous condition: Flatbush diabetes, also known as ketosis-prone diabetes (KPD).^[1]

First recognized in the 1980s and named in 1994 after a study of Black adults treated in the Flatbush neighborhood of Brooklyn,^[2] this form of diabetes continues to be under-recognized, even by healthcare professionals.

What Is Flatbush Diabetes?

Flatbush diabetes is a hybrid form of diabetes^[1] that shares features of both Type 1 and Type 2 diabetes. Like Type 1 diabetes, patients often present suddenly with diabetic ketoacidosis (DKA)—a life-threatening condition. Like Type 2 diabetes, many patients can eventually come off insulin and maintain control with oral medications or lifestyle changes.

This dual nature is what makes it dangerous—and frequently misdiagnosed.

Flatbush diabetes disproportionately affects:^[1]

• African Americans
• Afro-Caribbean populations
• Hispanic populations

It is now recognized globally, including across sub-Saharan Africa,^[3] but remains especially relevant in populations with higher rates of Type 2 diabetes and health disparities.

For many physicians, this condition represents a critical diagnostic blind spot. They simply don’t think of the diagnosis. That matters, because it is not rare: a recent review of the research found that about one in three adults who show up with new-onset diabetic ketosis have this ketosis-prone form.^[4]

The Clinical Presentation: A Dangerous First Impression

Patients with Flatbush diabetes often present with:

• Very high blood glucose levels
• Dehydration
• Nausea, vomiting, abdominal pain
• Confusion or altered mental status
• Diabetic ketoacidosis (DKA)

This presentation mimics classic Type 1 (insulin-dependent) diabetes, leading many doctors to assume lifelong insulin dependence. However, this assumption is often incorrect.

What Makes Flatbush Diabetes Different?

Flatbush diabetes has several defining features:

1. No Autoimmune Destruction

Unlike Type 1 diabetes, patients lack autoimmune markers such as GAD antibodies.

2. Reversible Insulin Deficiency

At diagnosis, insulin production appears severely impaired—but this is often temporary.

3. Potential for Remission

With proper treatment:

• Beta-cell function can recover
• Insulin may be discontinued within weeks to months
• Long-term management resembles Type 2 diabetes

This “reversible phase” is a hallmark of the condition.

Why Misdiagnosis Happens

Flatbush diabetes sits in a gray zone:

Feature	Type 1	Type 2	Flatbush
DKA at onset	Yes	Rare	Yes
Autoantibodies	Present	Absent	Absent
Insulin dependence	Lifelong	Sometimes	Often temporary

Because of this overlap, patients are frequently:

• Misclassified as Type 1
• Kept on unnecessary lifelong insulin
• Not counseled on remission potential

Implications for Black Health

Flatbush diabetes is more than a clinical curiosity—it is a health equity issue.

In communities with already high diabetes rates, delayed diagnosis and restricted access to specialty care can result in misdiagnosis. This leads to:

• Overtreatment or undertreatment
• Increased healthcare costs
• Poorer long-term outcomes

Recognizing Flatbush diabetes is precision medicine in action. Two simple blood tests — autoantibodies, and C-peptide, which shows how much insulin your own pancreas still makes — help sort out what kind of diabetes a patient actually has.^[5] That answer can decide whether someone needs insulin for life or can safely come off it. It is a clear example of why testing the individual beats assuming a diagnosis from the first impression.

Treatment Approach

Acute Phase (Emergency)

• Treat DKA aggressively with insulin, fluids, and electrolytes
• Stabilize the patient (same as Type 1 DKA protocols)
• Allow a recovery phase
• Reassess insulin needs frequently
• Evaluate C-peptide and autoantibodies
• Gradually taper insulin if appropriate

Long-Term Management

• Lifestyle intervention (nutrition, physical activity)
• Oral agents (e.g., metformin)
• Ongoing monitoring for relapses

Many patients achieve insulin independence (go off insulin), though continued follow-up is essential.

What Patients and Families Should Know

• Ask the right question. If you or a loved one was diagnosed with diabetes after an episode of DKA — especially as an adult — ask: “Was I tested for autoantibodies and C-peptide? Could this be ketosis-prone (Flatbush) diabetes?”
• Never stop insulin on your own. Coming off insulin is possible for many people with Flatbush diabetes, but it should only happen with your doctor’s guidance and close blood sugar monitoring.
• Remission is not a cure. Another episode of DKA can happen. Keep your follow-up visits, keep checking your blood sugar, and know the warning signs: nausea, vomiting, stomach pain, very fast breathing, or confusion. (Also know that the A1c test can read differently in some Black patients.)
• Your daily habits matter. Healthy eating, physical activity, and weight management help keep blood sugar in check and can help remission last.

What Clinicians Need to Do Differently

Think beyond Type 1 versus Type 2. Test for autoantibodies and beta-cell function (C-peptide). Reevaluate insulin needs over time rather than assuming lifelong dependence. And educate patients about both the possibility of remission and the risk of relapse.

Final Thoughts

Flatbush diabetes challenges our understanding of how to classify diabetes. It reminds us that not all diabetes fits neatly into categories—and failing to recognize that can cost lives. For clinicians serving Black populations, awareness of Flatbush diabetes is not optional—it is essential.

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References

1. Lebovitz HE, Banerji MA. Ketosis-prone diabetes (Flatbush diabetes): an emerging worldwide clinically important entity. Curr Diab Rep. 2018;18:120. link.springer.com/article/10.1007/s11892-018-1075-4
2. Banerji MA, et al. GAD antibody negative NIDDM in adult Black subjects with diabetic ketoacidosis and increased frequency of human leukocyte antigen DR3 and DR4: Flatbush diabetes. Diabetes. 1994;43(6):741-745. diabetesjournals.org/diabetes/article/43/6/741/8358/GAD-Anti…
3. Atypical diabetes subtypes in Black African populations. Diabetologia. 2026. pubmed.ncbi.nlm.nih.gov/41770244/
4. One third of cases of new-onset diabetic ketosis in adults are associated with ketosis-prone type 2 diabetes: a systematic review and meta-analysis. pubmed.ncbi.nlm.nih.gov/37888894/
5. Balasubramanyam A, Nalini R, Hampe CS, Maldonado M. Syndromes of ketosis-prone diabetes mellitus. Endocr Rev. 2008;29(3):292-302. pubmed.ncbi.nlm.nih.gov/18292467/