Lean Type 2 Diabetes Explained To Africans

By Chinonso Cynthia Ukah. BNSc, RN, RM, RPHN. Freelance Health Writer. Medically reviewed by: A. Odutola MB.BS, PhD.

A bare chested young African male wearing blue jeans and checking his waist circumference. Men are higher risk of lean type 2 diabetes because they tend to accumulate more abdominal fat even with a normal body weight. Image credit: Freepik.

 

Highlights 

• Slim people with normal Body Mass Index (BMI) can develop type 2 diabetes

• Even thin-looking people can have dangerous visceral fat stored around internal organs that triggers diabetes despite appearing lean on the outside.

• In lean type 2 diabetes, the pancreas (an organ in the belly that controls sugar levels in the body) stops producing enough insulin early on, unlike classic type 2 diabetes where insulin resistance comes first.

• Men and people of African, South Asian, and Hispanic backgrounds are more likely to develop lean diabetes, often around age 40.

• Poor nutrition and malnutrition in childhood puts the body at risk to develop lean diabetes decades later in adulthood.

• Healthcare providers can miss the diagnosis of lean diabetes because they assume only overweight people get type 2 diabetes, leading to delayed diagnosis and treatment.

 

Introduction 

It has become common for people to associate diabetes, especially type 2, with obesity. Whether a person has excess fat from birth or gained weight later in life, many people tend to assume that being overweight is the automatic trigger for diabetes.

However, not all fat people develop diabetes, and not all people with diabetes are fat. [1]

In fact, there's a less talked about group - lean individuals with type 2 diabetes. These are people who, despite having a normal or even underweight body size, develop type 2 diabetes mellitus (T2DM). [1] This challenges the stereotype that type 2 diabetes is strictly a “disease of the overweight.”

So, why does this happen? What makes slim individuals at risk for o a condition so strongly tied to excess weight? And what does this mean for diagnosis, treatment, and long-term health?

This article will explain what lean type 2 diabetes means and help you understand how to prevent diabetes in slim individuals.

 

What Is Lean Type 2 Diabetes?

Fig. 1: Basic definition of Lean Type 2 Diabetes. Click on tmage to enlarge. 

 

Lean Type 2 Diabetes (LT2D) is a form of type 2 diabetes that occurs in adults who are not overweight. These individuals have a body mass index (BMI) less than 25 kg/m², which is considered a normal weight. [2] See fig 1.

Unlike the typical presentation of type 2 diabetes, which is often linked to obesity and high insulin resistance, people with LT2D usually have:

• A normal or lean body weight
• A mild or moderate insulin resistance
• Weak beta cell (cells of the pancreas that make insulin) function

Despite these differences, LT2D still results in elevated blood sugar levels and carries a high risk of complications, especially those associated with the heart.

 

How Common is Lean Type 2 Diabetes?

Globally, the proportion of adults with diabetes who are lean  (BMI <25kg/m²) has been rising. A U.S. study revealed that the prevalence of diabetes among lean individuals increased from 4.5 percent in 2015 to 5.3 percent in 2020, while no increase was seen in people who were overweight and obese. 

More type 2 diabetes cases in some African countries occur in lean rather than obese people

 

In sub-Saharan Africa, lean individuals now make up a significant number of diabetes cases. A 2019 study reported that over 50 percent cases of type 2 diabetes occurred in people who are slim and a large portion of these people lived in urban areas. Another study found that in countries like South Africa and Zambia, two-thirds of the diabetic patients studied were lean.

Also, there are observations that diabetes is developing more in slim West Africans than in East and South Africans.

 

Causes of Lean Type 2 Diabetes

The exact cause of Lean Type 2 Diabetes (LT2D) is not fully understood, but studies point to two major causes:

1. Early beta cell failure

In LT2D, the pancreas fails to produce enough insulin early unlike the classic T2DM. This failure occurs even before insulin resistance becomes severe. This means that blood sugar rises because insulin is not enough, not necessarily because the body is resisting it. [1]

2. Hidden visceral fat

Researchers have discovered that visceral fat (fat stored deep in the abdomen around internal organs) can exist in people who appear slim. So, while someone may look lean on the outside, they could still have internal fat that triggers mild insulin resistance which contributes to the development of diabetes. [1]

 

Who is at Risk of Lean Type 2 Diabetes?

Certain groups of people are more likely to develop LT2D due to genetic, ethnic, and metabolic factors. The key risk groups are shown in Table 1:

Table 1: Key risk groups for Lean Type 2 Diabetes. Click on image to enlarge.

 

• People with a normal or low BMI: LT2D occurs in individuals with a body mass index (BMI) between 18 and 25 kg/m², a weight considered healthy.

• Adults around age 40: Although type 2 diabetes usually appears later in life, LT2D tends to show up earlier, often around age 40 or even younger in some ethnic groups. [3]

• Men: Studies show that men are more frequently affected than women, possibly due to their tendency to accumulate fat around their abdomen (visceral fat), which is more risky.

• Those with a family history of diabetes: Having a parent or sibling with diabetes significantly increases your risk, even if you’re not overweight.

• People from high-risk ethnic backgrounds: If you are South Asian (e.g. Indians, Pakistanis, and Bangladeshis), Sub-Saharan African, African American and Hispanic, your risk is higher.

• Individuals with low muscle mass or a history of early malnutrition: Malnourished children especially those with protein malnutrition or adults with low muscle mass are more likely to suffer from LT2D. 

• People with hidden (visceral) fat: Some slim individuals carry fat deep inside the abdomen. This invisible fat also known as thin-fat body composition is linked to insulin resistance even with a normal body weight. [3]

• Young adults in urbanizing or developing settings: In rapidly growing large cities, many young adults develop type 2 diabetes at a younger age despite not being obese. [1] This is likely due to adoption of western diets, stress, sedentary lifestyles, and early-life undernutrition. 

 

Signs and Symptoms 

Lean Type 2 Diabetes (LT2D) can be harder to detect because it does not fit the typical presentation of type 1 or 2 diabetes. But the symptoms caused by high blood sugar are still there. The key signs to watch out for are shown in fig. 2:

Fig. 2: Key symptoms and signs of Lean Type 2 Diabetes. Click on image to enlarge.

 

Diagnosis of Lean Type 2 Diabetes

Diagnosing LT2D can be challenging because it doesn’t present with the typical signs many healthcare professionals associate with type 2 diabetes. After taking your history and performing a physical assessment, your doctor may recommend these tests; 

1. Fasting plasma glucose also known as fasting blood sugar (FBS)
2. Oral glucose tolerance test (OGTT)
3. Glycated hemoglobin (HbA1c)
4. Random plasma glucose (RPG) or random blood sugar (RBS)
5. C-Peptide and insulin levels
6. Body Mass Index (BMI)
7. Urinalysis
8. Point-of-Care sugar checks with the glucometer

 

• Fasting blood sugar: This test is done after at least 8 hours of not eating, usually in the morning. If your result is 126 mg/dL (7.0 mmol/L) or higher, you have diabetes.

• Oral glucose tolerant test (OGTT): Your blood sugar is tested before and two hours after drinking a sugary glucose solution. If the 2-hour reading is 200 mg/dL (11.1 mmol/L) or higher, you have diabetes.

• Glycated haemoglobin: This measures your average blood sugar over the past 2 to 3 months. A result of 6.5% or higher means you likely have diabetes. However, this test may not be reliable if you have anaemia or blood disorders, which are common in some parts of Sub-Saharan Africa.

• Random blood sugar: This test can be done at any time of the day. If your result is 200 mg/dL or higher and you have symptoms like increased thirst, urination, or fatigue, you have diabetes.

• C-Peptide and Insulin Levels: These are more advanced tests that assess how much insulin your pancreas is producing and it helps to distinguish between Type 1 and Type 2 diabetes. These are, however, costly and rarely available in some hospitals in SSA.

• Body Mass Index (BMI): BMI is not a diagnostic tool but it is commonly used to assess diabetes risk. However, in LT2D, BMI is normal or low and this is why many LT2D cases go undetected. You can’t diagnose internal (visceral) fat or insulin resistance from BMI alone.

• Urinalysis: Helps to check for glucose or ketones in the urine, which may signal uncontrolled diabetes.

• Point-of-Care Sugar Checks with the Glucometer: The glucometer is a handheld device used to check sugar levels quickly and regularly anywhere, anytime.

 

Why is LT2D Often Misdiagnosed or Missed in sub-Saharan Africa?

• Normal body weight masks the risk: Most healthcare providers are trained to associate type 2 diabetes with overweight and obesity. As a result, slim individuals are often not screened, even when they present with classic symptoms.

• BMI can’t detect visceral fat: Most diabetes screening tools use Body Mass Index (BMI) to assess the risk but BMI only accounts for height and weight, not fat distribution. Someone can have a normal BMI and still carry high levels of visceral fat, especially around the liver and pancreas. This kind of hidden fat is a key trigger for insulin resistance in LT2D.

• There is limited access to diagnostic tests: In many rural or under-resourced health systems, key tests like OGTT, C-peptide, and HbA1c are expensive, scarce, or unavailable. Even basic glucometers may be faulty or uncalibrated.

• Inaccurate test results: Some tests, like HbA1c, are less reliable in populations with high anaemia rates, starvation, and infectious illnesses like HIV and malaria (common in sub-Saharan Africa). Similarly, fasting glucose tests may be affected by cultural fasting patterns or poor lab protocols.

• Misleading symptoms: Fatigue, weight loss, and frequent urination are symptoms of LT2D that are also seen in infections like TB, malaria, or HIV, and are more common in African settings. This leads to misdiagnosis or delayed attention to underlying blood sugar issues.

• Misclassification: Lean adults presenting with diabetes are often misdiagnosed as having type 1 diabetes or Latent Autoimmune Diabetes in Adults (LADA), especially when autoantibody or C-peptide tests are unavailable.

• Low awareness among health professionals: LT2D is not commonly taught in medical or nursing school curricula. Many healthcare workers, especially at the primary care level, don’t know it exists or don’t think to screen for it.

• Lack of public awareness: The public often assumes that only fat people get diabetes. Slim people may ignore early symptoms, thinking they’re immune due to their appearance. [2]

• Cultural perceptions of thinness: In some African communities, being slim is seen as a sign of illness (e.g., HIV/AIDS), while weight gain may be a sign of wealth or health. This may make people hesitant to report or seek care for unexplained weight loss.

 

Treatment for Lean Type 2 Diabetes

Treatment for LT2D usually involves a combination of medication and lifestyle changes, just like in regular type 2 diabetes. [2] Let's break it down:

Medications

• Metformin: This is often the first line treatment for LT2D and is a widely used insulin sensitizer. In Africa, it is available under various brand names.  

• Thiazolidinediones: These are also used to improve insulin sensitivity and are sold under brand names.

• Sulfonylureas: Your doctor may prescribe these drugs to boost insulin secretion from the pancreas. 

• DPP-4 inhibitors: These drugs are very expensive and include sitagliptin and vildagliptin.

• SGLT-2 inhibitors: These may also be prescribed. Brand and generic versions of empagliflozin and dapagliflozin are the two most commonly available in African markets.

Lifestyle Changes

• Diet: Eating balanced meals that include local, low glycemic index foods such as legumes, whole grains, and vegetables helps to maintain blood sugar at normal levels. 

• Physical activity: Even for slim individuals, regular exercise helps reduce internal (visceral) fat and improves how the body uses insulin. Activities like walking, dancing, or farming tasks can be very effective.

• Community-based lifestyle programs: Initiatives like walking in groups, health talks, and peer support clubs help improve consistency with lifestyle changes.

• Culturally relevant education: Teaching people in a way that respects their beliefs and eating habits makes it more likely that they’ll listen and follow through with health advice.

• Public health strategies: Policies that promote access to healthy foods, create safe spaces for exercise, and integrate diabetes awareness into schools and workplaces are critical for long-term impact.

 

Complications of Lean Type 2 Diabetes 

Just like classic Type 2 Diabetes, Lean Type 2 Diabetes (LT2D) can lead to serious long-term health complications often with even faster progression because diagnosis has been delayed or missed.

Common complications include:

• Heart disease including heart attacks, stroke, and high blood pressure.
• Kidney damage (nephropathy) which may lead to kidney failure.
• Nerve damage (neuropathy) which causes numbness, tingling, or pain, especially in the feet.
• Eye damage (retinopathy) which can lead to blurry vision or blindness.
• Frequent infections such as urinary tract infections, gum infections, and skin infections.
• Slow wound healing which increases the risk of ulcers and amputations.
• Mental health issues including depression and anxiety due to late diagnosis or stigma.
• Sexual dysfunction such as reduced libido or erectile dysfunction, especially in men.
• Fatigue and reduced quality of life due to poor blood sugar control.
• Higher risk of early death from undiagnosed or poorly managed complications. [2]

 

Prevention Tips for Lean Type 2 Diabetes 

Table 2: showing summary prevention tips for Lean Type 2 Diabetes. Click on iamge to enlarge.

 

1. Check your blood sugar regularly especially when you go for checkups. Do not assume that you are safe from diabetes simply because you are slim.

2. Limit the intake of refined carbohydrates and sugary drinks.

3. Eat balanced meals that have low glycaemic index, contain lean protein, whole grains, vegetables, and healthy fats to maintain stable blood sugar.

4. Stay physically active by engaging in regular aerobic and strength-training exercises.

5. Monitor your waist circumference especially if you are a man. A larger waistline may indicate hidden visceral fat, which increases LT2D risk.

6. Sleep well and manage your stress levels. Chronic stress and poor sleep can lead to insulin resistance regardless of your weight.

7. Reduce your intake of alcohol and smoking as both can worsen insulin sensitivity and increase your risk of metabolic disorders.

8. Know your body. If you start experiencing frequent urination, fatigue, blurry vision, or unexplained weight loss, this should prompt a diabetes screening, even if you're slim.

9. If diabetes runs in your family, get screened early and often.

10. Avoid skipping meals

11. Do not engage in extreme or unnecessary dieting in the name of weight loss challenges especially if you are already slim. This can stress the body and impair metabolic function.

12. Participate in local awareness programs like community-based diabetes education

If you are a mother and you are slim,

13. Eat well during pregnancy

14. Prevent and treat malnutrition in your children as early as possible

15. Encourage exclusive breastfeeding for the first 6 months

16. Mothers with a history of gestational diabetes should monitor their children's growth and glucose levels regularly.

 

Conclusion 

Lean Type 2 Diabetes (LT2D) is a lesser-known form of diabetes that affects individuals who are not overweight. Unlike the typical type 2 diabetes that is strongly linked to obesity, LT2D can affect slim and normal weight people and go undetected for years.

One of the biggest myths surrounding diabetes is that being slim means you are safe from diabetes. However, hidden visceral fat, poor early-life nutrition, and genetic factors can trigger this condition even in individuals with a normal BMI. This often leads to missed diagnoses, late treatment, and worse health outcomes. That’s why slim individuals, especially those with a family history of diabetes, signs like fatigue, frequent urination, or unexplained weight loss should not ignore the possibility of a diabetes diagnosis.

Early screening, even in the absence of excess weight, can detect LT2D before complications set in. To prevent LT2D, engage in good nutrition practices early in life, regular physical activity, stress management, and routine health checks.

For mothers, especially during pregnancy, proper nutrition can help reduce long-term diabetes risk in their children.

 

References 

1. Salvatore T, Galiero R, Caturano A, Rinaldi L, Criscuolo L, Di Martino A, et al. Current knowledge on the pathophysiology of lean/normal-weight type 2 diabetes. Int J Mol Sci. 2022;24(1):658. doi:10.3390/ijms24010658. Available from here. 

2. Ogunjobi TT, Adeyanju SA, Akinwande KG, Obasi DE, Aigbagenode AA, Musa A, et al. Improving the prevention and treatment of Lean Type 2 Diabetes in Sub-Saharan Africa: A review. Eur J Sustain Dev Res. 2025;9(2):em0287. doi:10.29333/ejosdr/16288. Available from here.

3. George AM, Jacob AG, Fogelfeld L. Lean diabetes mellitus: An emerging entity in the era of obesity. World J Diabetes. 2015;6(4):613–620. doi:10.4239/wjd.v6.i4.613. Available from here.

 

Related: 

Type 1 Diabetes Mellitus: An Explainer for Africans

Type 2 Diabetes: What Africans Need to Know

Diabetes in Pregnancy in Sub-Saharan Africa: An Overview

You May Have Prediabetes and Not Know. How to Find Out (Tips)

Management of Type 2 Diabetes in Nigeria

Childhood Diabetes in Sub-Saharan Africa: Type 1

Type 2 Diabetes Mellitus in African Children 

 

 

Published: September 3, 2025

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