Aims/Hypothesis We undertook phenotypic characterization of early-onset and late-onset type 2 diabetes (T2D) in adult Black African and White European populations with recently diagnosed T2D to explore ethnic differences in the manifestation of early-onset T2D.

Methods Using the Uganda Diabetes Phenotype study cohort of 500 adult Ugandans and the UK StartRight study cohort of 714 White Europeans with recently diagnosed islet autoantibody negative type 2 diabetes, we compared the phenotypic characteristics of participants with early-onset T2D (diagnosed at <40 years) and late-onset T2D (diagnosed at ≥40 years).

Results One hundred and thirty four adult Ugandans and 113 White Europeans had early-onset T2D. Compared with late-onset T2D, early-onset T2D in White Europeans was significantly associated with a female predominance (52.2% vs. 39.1%, p=0.01), increased body mass index (mean [95% CI]-36.7 [35.2-38.1] kg/m2 vs. 33.0 [32.4-33.6] kg/m2, p<0.001), waist circumference (112.4 [109.1-115.6] cm vs. 108.8 [107.6-110.1] cm, p=0.06), and a higher frequency of obesity (82.3% vs. 63.4%, p<0.001). No difference was seen with the post-meal C-peptide levels as a marker of beta-cell function (mean [95% CI]-2130.94 [1905.12-2356.76] pmol/L vs. 2039.72 [1956.52-2122.92], p=0.62).

Conversely, early-onset T2D in Ugandans was associated with less adiposity (mean [95% CI] waist circumference-93.1 [89.9-96.3] cm vs. 97.4 [95.9-98.8] cm, p=0.006) and a greater degree of beta-cell dysfunction (120-minute post-glucose load C-peptide mean (95% CI) level-896.08 [780.91-1011.24] pmol/L vs 1310.10 [1179.24-1440.95] pmol/L, p<0.001), without female predominance (53.0% vs. 57.9%, p=0.32) and differences in the body mass index (mean [95% CI]-27.3 [26.2-28.4] kg/m2 vs. 27.9 [27.3-28.5] kg/m2, p=0.29).

Conclusions/Interpretation These differences in the manifestation of early-onset T2D underscore the need for ethnic-specific therapeutic and preventive approaches for the condition.

What is already known about this subject?

Globally, the burden of early-onset type 2 diabetes (T2D) is rapidly increasing.

Evidence from studies conducted in Asians and White populations of European ancestry has shown that early-onset T2D is characterized by a female preponderance, increased obesity, rapid decline in the beta-cell function, and a high prevalence of diabetes-related complications.

What is the key question?

What are the new findings?

Striking differences in the manifestation of early-onset type 2 diabetes were observed in adult Ugandans and White Europeans with recently diagnosed type 2 diabetes.

Early-onset type 2 diabetes in adult White populations of European ancestry was characterized by female predominance and increased adiposity. In contrast, less adiposity, lower pancreatic beta-cell function, and absence of female predominance were observed in adult Ugandans with early-onset type 2 diabetes.

How might this impact on clinical practice in the foreseeable future?

The authors have declared no competing interest.

The study was funded by the UK Medical Research Council and the UK Department for International Development, and the National Institute for Health Care Research, and the Diabetes UK.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Ethics committee of Uganda Virus Research Institute, Uganda National Council of Science and Technology, and the South West Cornwall and Plymouth NHS gave ethical approval for this work.

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I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

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All data produced in the present study are available upon reasonable request to the authors