Diabetic nephropathy in Africa: A systematic review

Table 1 Search history PubMed

Search	Search terms	Hits
1	Diabetes[tw] OR Diabetes mellitus[tw] OR Type 1 diabetes[tw] OR Type 1 diabetes mellitus[tw] OR T1DM[tw] OR Type 2 diabetes[tw] OR Type 2 diabetes mellitus[tw] OR T2DM[tw] OR Hyperglycemia[tw] OR Glucose intolerance[tw]	445204
2	Renal insufficiency[tw] OR Renal failure[tw] OR Renal injury[tw] OR Renal disease[tw] Kidney insufficiency[tw] OR Kidney failure[tw] OR Kidney injury[tw] OR Kidney disease[tw] OR End-stage renal disease[tw] OR End-stage renal failure[tw] OR End-stage kidney disease[tw] OR End-stage kidney failure [tw] OR End stage renal disease[tw] OR End stage renal failure[tw] OR End stage kidney disease[tw] OR End stage kidney failure [tw] OR Microalbuminuria [tw] OR Micro-albuminuria OR Macroalbuminuria [tw] or Macro-albuminuria [tw]	154354
3	# 1 AND # 2	20388
4	Diabetic nephropathy [MeSH Terms]	19406
5	# 3 OR # 4	34221
6	((((("Africa"[MeSH] OR Africa*[tw] OR Algeria[tw] OR Angola[tw] OR Benin[tw] OR Botswana[tw] OR "Burkina Faso"[tw] OR Burundi[tw] OR Cameroon[tw] OR "Canary Islands"[tw] OR "Cape Verde"[tw] OR "Central African Republic"[tw] OR Chad[tw] OR Comoros[tw] OR Congo[tw] OR "Democratic Republic of Congo"[tw] OR Djibouti[tw] OR Egypt[tw] OR "Equatorial Guinea"[tw] OR Eritrea[tw] OR Ethiopia[tw] OR Gabon[tw] OR Gambia[tw] OR Ghana[tw] OR Guinea[tw] OR "Guinea Bissau"[tw] OR "Ivory Coast"[tw] OR "Cote d'Ivoire"[tw] OR Jamahiriya[tw] OR Jamahiryia[tw] OR Kenya[tw] OR Lesotho[tw] OR Liberia[tw] OR Libya[tw] OR Libia[tw] OR Madagascar[tw] OR Malawi[tw] OR Mali[tw] OR Mauritania[tw] OR Mauritius[tw] OR Mayote[tw] OR Morocco[tw] OR Mozambique[tw] OR Mocambique[tw] OR Namibia[tw] OR Niger[tw] OR Nigeria[tw] OR Principe[tw] OR Reunion[tw] OR Rwanda[tw] OR "Sao Tome"[tw] OR Senegal[tw] OR Seychelles[tw] OR "Sierra Leone"[tw] OR Somalia[tw] OR "South Africa"[tw] OR "St Helena"[tw] OR Sudan[tw] OR Swaziland[tw] OR Tanzania[tw] OR Togo[tw] OR Tunisia[tw] OR Uganda[tw] OR "Western Sahara"[tw] OR Zaire[tw] OR Zambia[tw] OR Zimbabwe[tw] OR "Central Africa"[tw] OR "Central African"[tw] OR "West Africa"[tw] OR "West African"[tw] OR "Western Africa"[tw] OR "Western African"[tw] OR "East Africa"[tw] OR "East African"[tw] OR "Eastern Africa"[tw] OR "Eastern African"[tw] OR "North Africa"[tw] OR "North African"[tw] OR "Northern Africa"[tw] OR "Northern African"[tw] OR "South African"[tw] OR "Southern Africa"[tw] OR "Southern African"[tw] OR "sub Saharan Africa"[tw] OR "sub Saharan African"[tw] OR "subSaharan Africa"[tw] OR "subSaharan African"[tw]) NOT ("guinea pig"[tw] OR "guinea pigs"[tw] OR "aspergillus niger"[tw])))))	354928
7	# 5 AND # 6	1065
8	#4 Limits: 1994/01/01 to 2014/10/22 and studies done in Humans	918

Table 2 General characteristics of studies of chronic kidney disease in people with diabetes in Africa

Ref.	Country	Period	Design	Setting	Sample size	Mean or median age (yr)	Male (%)	Type and duration of diabetes (yr)	Duration FUP	Method for CKD assessment
										Proteinuria	MDRD	Urine ACR	Cockroft-Gault
Motala et al[37], 2001	South Africa	Not precised	Retrospective cohort study	Clinic, urban	219	39.5 T1DM; 58.4 T2DM	19.6	16.10 T1DM; 18.6 T2DM	At least 10 yr	persistent proteinuria (Dipstick)
Elbagir et al[26], 1995	Sudan	Jan-July 1992	Cross-sectional, self-selected sampling	Clinic, urban	128	31.5 (15-75)	48.4	Insulin-treated; 9 (1-40)	NA	Proteinuria (Dipstick)
Sobngwi et al[44], 1999	Cameroon	Not precised	Cross-sectional, self-selected sampling	Clinic, urban	64	37.4 normotensive T1DM; 51.7 normotensive T2DM; 57.9 hypertensive T1DM	57.8	6.7 normotensive T1DM; 4.7 normotensive T2DM; 4.8 hypertensive T1DM	NA	Proteinuria
Katchunga et al[30], 2010	DR congo	2005-2007	Cross-sectional, self-selected sampling	Clinic, urban	98	58 (10.4)	35.7	7.3 T2DM	NA		MDRD (corrected for Blacks)
Choukem et al[22], 2012	Cameroon	Jan 2008- Oct 2010	Cross-sectional, self-selected sampling	Clinic, urban	420	56.7	49	4 (1-9) T2DM	NA	Proteinuria (Dipstick)
Keeton et al[31], 2004	South Africa	Not precised	Prospective cohort, self-selected sampling	Clinic, urban	59	62	35.6	17.8 T2DM	12 yr			Urine ACR
Pruijm et al[39], 2008	Seychelles	2004	Cross-sectional; random sex and age-stratified sample	Population	1218 (whole sample, including diabetic patients)	Not precised	45.9	Newly diagnosed patients	NA			Urine ACR
Alebiosu[16], 2003	Nigeria	Jan 2000 June 2001	Cross-sectional, self-selected sampling	Clinic, urban	342	6.5 T1DM; 9.4 T2DM	53.8	26 T1DM; 53.4 T2DM	NA	Persistent proteinuria
Bouaziz et al[20], 2012	Tunisia	Jan 2008Dec 2010	Cross-sectional, self-selected sampling	Clinic, urban	73	59.3	23.3	T2DM 10.6	NA	Proteinuria
Ajayi et al[15], 2014	Nigeria	Not precised	Retrospective cross-sectional	Clinic, urban	65	Not available	Not available	T2DM	NA		MDRD
Levitt et al[32], 1997	South Africa	July-December 1992	Cross-sectional, stratified random sampling	Clinic, urban	243	56.4	38.3	8 T2DM and T1DM	NA	Persistent proteinuria		Urine ACR
Majaliwa et al[34], 2007	Tanzania	June 2005- Feb 2006	Cross-sectional, self-selected sampling	Clinic, urban	99	12.6	42.4	4.76 T1DM	NA	Proteinuria
Marshall et al[36], 2013	Rwanda	June 2009-Nov 2010	Cross-sectional, self-selected sampling	Clinic, urban	286	18.6	46.5	3.4 T1DM	NA	Proteinuria		Urine ACR
Alebiosu et al[18], 2003	Nigeria	Sept 1999- August 2002	Cross-sectional, self-selected sampling	Clinic, urban	465	Not precised	Not precised	T2DM	NA	Proteinuria
Gill et al[28], 2005	South Africa	From 1982 to 2002	Prospective cohort, self-selected sampling	Clinic, urban	88	22 at onset	52	T1DM	20 yr
Djrolo et al[24], 2001	Benin	Not indicated	Cross-sectional	Clinic, urban	152	53.3	65.8	T1DM and T2DM	NA	Proteinuria
Rotchford et al[43], 2002	South Africa	1999	Cross-sectional, self-selected sampling	Clinic, rural	253	56.5	26.9	42.2; T1DM and T2DM	NA			Urine ACR
Rissassi et al[42], 2009	DR congo	11 june 2008 to 30 july 2008	Cross-sectional, self-selected sampling	Clinic, urban	181	19.1	38.7	57.6 T1DM	NA			Urine ACR
Rahlenbeck et al[40], 1997	Ethiopia	January - April 1995	Cross-sectional, self-selected sampling	Clinic, urban	170	31.4 T1DM; 56.7 T2DM	60	5.9 T1DM; 6.0 T2DM	NA	Proteinuria
Wanjohi et al[45], 2002	Kenya	June 2000 - January 2001	cross-sectional, self-selected sampling	Clinic, urban	100	53.7	37	10.3 T2DM	NA	Albuminuria
Nambuya et al[38], 1996	Uganda	1 January 1993 - 10 August 1994	Cross-sectional, self-selected sampling	Clinic, urban/urban (origin of participants)	252	Not precised	46.4	45 (range 30-69)T2DM and T1DM	NA	Proteinuria
Rasmussen et al[41], 2013	Zambia	February - April 2011	Cross-sectional, self-selected sampling	Clinic, rural	101	50 (range 50-68)	37.3	T2DM and T1DM	NA			Urine ACR
Bentata et al[19], 2013	Morocco	From September 2006	Prospective cohort study	Clinic, urban	72	29.5	69.4	17 (11-20) T1DM	5 yr	Proteinuria	MDRD
Gill et al[27], 2008	Ethiopia	Not precised	Cross-sectional, self-selected sampling	Clinic, rural	105	41	70.5	7 T1DM and T2DM	NA			Urine ACR
Bouzid et al[21], 2011	Tunisia	June 2006 - July 2008	Cross-sectional, self-selected sampling	Clinic, urban	689	60	39.3	11 T2DM	NA	Proteinuria			Cockroft-Gault
Janmohamed et al[29], 2013	Tanzania	October 2011 - March 2012	Cross-sectional, self-selected sampling	Clinic, urban	369	54 (IQR 45-62)	46.6	6 (3-11)T1DM (6.2%) and T2DM (93.8%)	NA				Cockroft-Gault
Danquah et al[23], 2012	Ghana	August 2007 - June 2008	Cross-sectional, self-selected sampling	Clinic, urban	675	54.7	25	T2DM	NA	Proteinuria
Lutale et al[33], 2007	Tanzania	July 2003 - March 2004	Cross-sectional, self-selected sampling	Clinic, urban	244	T1DM 21(range 4-44.8)T2DM 53 (range 23.5-85)	46.3	T1DM 3 (0-17)T2DM 4 (range 0-25)	NA	Proteinuria			Cockroft-Gault
Worku et al[46], 2010	Ethiopia	October 2008	Cross-sectional, self-selected sampling	Clinic, urban	305	44.4	62.9	T1DM and T2DM; 53.4% less than 5 yr and 33.8% 5-9 yr	NA	Proteinuria
Makulo et al[35], 2010	DR Congo	30 March - 24 April 2007	Cross-sectional, self-selected sampling	Population-based, Urban	81	Not precised	Not precised	No precision	NA		MDRD	Urine ACR
Eghan et al[25], 2007	Ghana	January - July 2005	Cross-sectional, self-selected sampling	Clinic, urban	109	54.1	28	T1DM and T2DM 10.7	NA	Proteinuria
Alebiosu et al[17], 2004	Nigeria	January 2000 - June 2001	Case (T2DM with persistent proteinuria-control (T2DM patients nephropathy)	Clinic, urban	162	53.4	50	T2DM9.4 cases, 5.5 controls	NA

ACR: Albumin-to-Creatinine Ratio; FUP: Follow-up; MDRD: Modification of diet renal disease; NA: Not applicable.

Table 3 Prevalence and incidence of chronic kidney disease in people with diabetes across studies in Africa

Ref.	Country	Sample size	Type of diabetes	Duration of follow-up	Diagnostic criteria for CKD	Prevalence	Incidence	Comments
Motala et al[37], 2001	South Africa	219	T1DM and T2DM	16.10 (4.9) T1DM; 18.6 (5.7) T2DM; at least 10 yr	Persistent proteinuria (dipstix proteinuria on three or more consecutive occasions over 18 mo in the at absence of infection or cardiac failure)	Not applicable	24.6%
Elbagir et al[26], 1995	Sudan	128	Insulin-treated	Not applicable	Proteinuria (≥ 30 mg/dL)	22%	Not applicable
Sobngwi et al[44], 1999	Cameroon	64	T1DM and T2DM	Not applicable	Proteinuria	53.1%	Not applicable
Katchunga et al[30], 2010	DR Congo	98	T2DM	Not applicable	MDRD: CKD stage ≥ 2 according to the National Kidneyfoundation	18.1%	Not applicable
Choukem et al[22], 2012	Cameroon	420	T2DM	Not applicable	Proteinuria (30 mg/24 h)	31%	Not applicable
Keeton et al[31], 2004	South Africa	59	T2DM	12 yr	Urine Albumin-to-Creatinine Ratio (no detail)		After 12 yr of follow-up or death, 94.9% (56/59) had a proteinuria with a mean duration from diabetes onset to proteinuria of 9.7 (5.9) yr	83% (49/59) had an elevated SCr atthe end of the study and in 66.1% (39/59) the SCr level had doubled during the study
Pruijm et al[39], 2008	Seychelles	1218	All types	Not applicable	Microalbuminuria: Urine Albumin-to-Creatinine Ratio 3.4-33.9 mg albumin/mmol creatinine	36.1%	Not applicable
Alebiosu[16], 2003	Nigeria	342	T1DM and T2DM	Not applicable	Persistent proteinuria	28.4%	Not applicable
Bouaziz et al[20], 2012	Tunisia	73	T2DM	Not applicable	Microalbuminuria: < 2.8 g/mol for women and < 2.3 g/mol for men	11%	Not applicable
Ajayi et al[15], 2014	Nigeria	65	T2DM	Not applicable	MDRD: eGFR ≤ 60 mL/min per 1.73 m2	43.1%	Not applicable
Levitt et al[32], 1997	South Africa	243	T2DM and T1DM	Not applicable	Urine Albumin-to-Creatinine Ratio > 3.4 mm/mmol	36.7%	Not applicable
					Persistent proteinuria (for at least 3 consecutive visits)	5.3%
Majaliwa et al[34], 2007	Tanzania	99	T1DM	Not applicable	Proteinuria (no detail)	29.3%	Not applicable
Marshall et al[36], 2013	Rwanda	286	T1DM	Not applicable	Microalbuminuria: Urine Albumin-to-Creatinine Ratio = 30-299 mg/gMacroalbuminuria or overt nephropathy: Urine Albumin-to-Creatinine Ratio ≥ 300 mg/g	Microalbuminuria: 21%; Macroalbuminuria: 5%	Not applicable
Alebiosu et al[18], 2003	Nigeria	465	T2DM	Not applicable	Proteinuria and eGFR	41.1%	Not applicable	The method for the estimation of the GFR is not indicated
Gill et al[28], 2005	South Africa	88	T1DM	20 yr	Persistent dipstick proteinuria		Death of renal cause after 20 yr = 18.4% (9/49)	Death due to chronic renal failure after 20 yr of follow-up was 9/49 (after exclusion of lost to follow)
Djrolo et al[24], 2001	Benin	152	T1DM and T2DM	Not applicable	Proteinuria (no detail)	20%	Not applicable
Rotchford et al[43], 2002	South Africa	253	T1DM and T2DM	Not applicable	Microalbuminuria > 2.5 mg/mmol in men or 3.5 mg/mmol in women	46.4%	Not applicable
Rissassi et al[42], 2009	DR congo	181	T1DM	Not applicable	Microalbuminuria: Urine Albumin-to-Creatinine Ratio = 30-299 mg/gMacroalbuminuria: Urine Albumin-to-Creatinine Ratio ≥ 300 mg/g	21.9% (microalbuminuria) and 7.3% (macroalbuminuria)	Not applicable
Rahlenbeck et al[40], 1997	Ethiopia	170	T1DM and T2DM	Not applicable	Microalbuminuria: > 30 mg/LMacroalbuminuria: > 300 mg/L	T1DM: 32% (microalbuminuria) and 15% (macroalbuminuria)T2DM: 37% (microalbuminuria) and 20% (macroalbuminuria)	Not applicable
Wanjohi et al[45], 2002	Kenya	100	T2DM	Not applicable	Proteinuria ≥ 20 mg	26%	Not applicable
Nambuya et al[38], 1996	Uganda	252	T1DM and T2DM	Not applicable	Proteinuria (no detail)	17.1%	Not applicable	Newly diagnosed patients
Rasmussen et al[41], 2013	Zambia	101	T1DM and T2DM	Not applicable	Microalbuminuria: ACR = 3.5-35.0 for women and 2.5-25.0 mg/mmol for menMacroalbuminuria were ACR> 35.0 for women and > 25.0 for men	Microalbuminuria: 23.8%Macroalbuminuria: 8.9%	Not applicable	There were 33 patients with diabetes alone, and 68 patients with diabetes and hypertension
Bentata et al[19], 2013	Morocco	72	T1DM	5 yr	Microalbuminuria: albumin excretion rate 30-300 mg/24 hMacroalbuminuria: albumin excretion rate > 300 mg/24 hNephrotic proteinuria: albumin excretion rate ≥ 3000 mg/24 hRenal failure: eGFR < 60 mL/min (MDRD)	At the time of enrollementMicroalbuminuria: 48.6%Macroalbuminuria: 36.1%Nephrotic proteinuria: 15.3%	The incidence of end stage renal disease after 5 yr: 34.7%	Urinary assays done onadmission were repeated on three specimens atthree-monthly intervals
Gill et al[27], 2008	Ethiopia	105	T1DM and T2DM	Not applicable	Nephropathy: ACR> 25.0 mg/mmol and retinopathy presentMicroalbuminuria: ACR> 2.5 and < 25.0 mg/mmol in men and > 3.5 and< 25.0 mg/mmol in women	Nephropathy: 2%Microalbuminuria: 51%		Urinary ACR levels (toassess microalbuminuria and nephropathy) were done on59 patients, as those with haematuria and/or urinary infection were excluded
Bouzid et al[21], 2011	Tunisia	689	T2DM	Not applicable	CKD: eGFR < 60 mL/min per 1.73 m2 (Cockroft-Gault)Microalbuminuria: albumin excretion rate 30-300 mg/24 hMacroalbuminuria: albumin excretion rate > 300 mg/24 h	CKD: 19.8%Microalbuminuria: 13%Macroalbuminuria: 10.1%	Not applicable	Macroalbuminuria was significantly associated with CKD (P < 0.00001)
Janmohamed et al[29], 2013	Tanzania	369	T1DM and T2DM	Not applicable	CKD: eGFR < 60 mL/min per 1.73 m2 (Cockroft-Gault) or microalbuminuria (> 20 mg/L) or overt protienuria	CKD: 83.7%eGFR < 60 mL/min per 1.73 m2: 24.7%Microalbuminuria: 45.8%Overt proteinuria: 34.1%	Not applicable
Danquah et al[23], 2012	Ghana	671	T2DM	Not applicable	Proteinuria ≥ 20 mg/L	43%	Not applicable
Lutale et al[33], 2007	Tanzania	244	T1DM and T2DM	Not applicable	Microalbuminuria: AER 20-200 μg/minMacroalbuminuria: AER > 200 μg/minRenal failure: eGFR < 60 mL/min per 1.73 m2:	Microalbuminuria: 12.1% (T1DM); 9.8% (T2DM)Macroalbuminuria: 1.1% (T1DM); 7.2% (T2DM)Renal failure: 4.6% (T1DM); 22% (T2DM)	Not applicable
Worku et al[46], 2010	Ethiopia	305	T1DM (38%) and T2DM (62%)	Not applicable	Proteinuria (no detail)	15.7%	Not applicable
Makulo et al[35], 2010	DR Congo	81	No precision	Not applicable	Microalbuminuria: ACR 30-299 mg/gMacroalbuminuria: ACR ≥ 300 mg/gRenal failure: eGFR < 60 mL/min per 1.73 m2	Microalbuminuria: 43.5%Macroalbuminuria: 12%Renal failure: 21.4%	Not applicable
Eghan et al[25], 2007	Ghana	109	T1DM and T2DM	Not applicable	Microalbuminuria: ACR 30-300 mg/g	43.1%	Not applicable
Alebiosu et al[17], 2004	Nigeria	162	T2DM	Not applicable	Not applicable	Not applicable	Not applicable	The study did not assess the prevalence or incidence of diabetic nephropathy, but its predictors

ACR: Albumin-to-Creatinine Ratio; T1DM: Type 1 diabetes mellitus; T2DM: Type 2 diabetes mellitus; CKD: Chronic kidney disease; eGFR: Epidermal growth factor receptor.

Table 4 Risk factors for chronic kidney disease in people with diabetes

Ref.	Country	Sample size	Type of diabetes	Diagnostic criteria for CKD	Risk factor	Measure of association		Factors adjusted for	Comments
						Effect size	P-value
Motala et al[37], 2001	South Africa	219	T1DM and T2DM	Persistent proteinuria	Not assessed
Elbagir et al[26], 1995	Sudan	128	Insulin-treated	Proteinuria	Age		P = 0.006
					Duration of diabetes		P = 0.003
					Systolic BP		P = 0.0001
					Diastolic BP		P = 0.001
					Serum cholesterol		P < 0.05
Sobngwi et al[44], 1999	Cameroon	64	T1DM and T2DM	Proteinuria	Duration of diabetes		P = 0.04
					Diastolic BP		P = 0.01
Katchunga et al[30], 2010	DR Congo	98	T2DM	MDRD (corrected for Blacks); CKD stage ≥ 1 according to the National Kidneyfoundation	Hypertension	aOR: 2.49 (0.98-6.34)	P = 0.04	Age, duration of diabetes, BMI
Choukem et al[22], 2012	Cameroon	420	T2DM	Proteinuria (30 mg/24 h)	Systolic BP	aOR: 1.45 (1.15-1.84)	P = 0.006
					Diastolic BP	aOR: 1.33 (1.06-1.66)	P = 0.026
					Pulse pressure	aOR: 1.35 (1.06-1.71)	P = 0.0007
					Mean arterial pressure	aOR: 1.42 (1.13-1.78)	P = 0.006
Keeton et al[31], 2004	South Africa	59	T2DM	Urine Albumin-to-Creatinine Ratio (no detail)	High entry serum creatinine		P < 0.006		These are risk factors for death from chronic renal failure (compared with the patients who were still alive at follow-up)By the end of study 47 of the 59 patients had died; the cause of death not established in 2 patients. Death was due to chronic renal failure in 17 cases
					BMI < 28		P < 0.003
					Severe retinopathy		P < 0.002
					Mean glucose level of > 14 mmol/L		P < 0.035
Pruijm et al[39], 2008	Seychelles	1218	All types	Microalbuminuria: Urine Albumin-to-Creatinine Ratio 3.4-33.9 mg albumin/mmol creatinine	Not assessed				Risk factors were investigated in the whole study population in both diabetics and non-diabetics
Alebiosu[16], 2003	Nigeria	342	T1DM and T2DM	Persistent proteinuria	Not assessed
Bouaziz et al[20], 2012	Tunisia	73	T2DM	Microalbuminuria: < 2.8 g/mol for women and < 2.3 g/mol for men	Family history of nephropathy		P = 0.0289		Comparison of T2DM patients with nephropathy with those without nephropathy
					Smoking		P = 0.0056
					Insulin therapy		P = 0.0310
					Glitazones therapy		P = 0.0115
					Anti-hypertensives (not ACE inhibitor)		P < 0.0001
					Lipid-lowering agents		P < 0.0001
Ajayi et al[15], 2014	Nigeria	65	T2DM	MDRD: eGFR ≤ 60 mL/min per 1.73 m2	Not assessed
Levitt et al[32], 1997	South Africa	243	T2DM and T1DM	Urine Albumin-to-Creatinine Ratio > 3.4 mm/mmol	Not assessed
				and Persistent proteinuria (for at least 3 consecutive visits)
Majaliwa et al[34], 2007	Tanzania	99	T1DM	Proteinuria (no detail)	Missing insulin doses		P = 0.045	Not available
Marshall et al[36], 2013	Rwanda	286	T1DM	Microalbuminuria: Urine Albumin-to-Creatinine Ratio = 30-299 mg/g	Age (increase)	aOR: 0.86, 95%CI: 0.77-0.96	P = 0.009	Each variable is adjusted for the others	These are risk factors of microalbuminuria. There was no factor associated to macroalbuminuria
					Duration of diabetes (one year increase)	aOR: 0.86, 95%CI: 0.77-0.96	P = 0.008
					Diastolic BP (increase)	aOR: 0.86, 95%CI: 0.77-0.96	P = 0.004
					HBA1c (increase)	aOR: 0.86, 95%CI: 0.77-0.96	P = 0.047
Alebiosu et al[18], 2003	Nigeria	465	T2DM	Proteinuria and eGFR (no detail)	Hypertension, left ventricular hypertrophy, stroke and myocardial infarction were more frequent in advanced stages of nephropathy	Not available	P < 0.05	Not available	Patients with advanced stages of nephropathy (IV and V) were compared with those with stages ≤ III
Gill et al[28], 2005	South Africa	88	T1DM	Persistent dipstick proteinuria	Not assessed
Djrolo et al[24], 2001	Benin	152	T1DM and T2DM	Proteinuria (no detail)		Not available	Not available	Not available	Proteinuria was more frequent in insulin-treated patients compared those on oral antidiabetic treatment. The prevalence of proteinuria also increased with the duration of diabetes
Rotchford et al[43], 2002	South Africa	253	T1DM and T2DM	Microalbuminuria > 2.5 mg/mmol in men or 3.5 mg/mmol in women	Duration of diabetes > 10 yr	4.19 (1.93-9.10)	< 0.001	Model contains duration of diabetes, BMI, HbA1c, age andhypertension
					BMI > 33	0.27 (0.08-0.48)	0.002
					HbA1c > 14%	4.69 (1.65-13.3)	0.004
					Hypertension	2.11 (1.07-4.17)	0.031
Rissassi et al[42], 2009	DR congo	181	T1DM	Microalbuminuria: Urine Albumin-to-Creatinine Ratio = 30-299 mg/gMacroalbuminuria: Urine Albumin-to-Creatinine Ratio ≥ 300 mg/g	Duration of diabetes > 5 yr	4.1 (1.9-8.4)		No precision
					Age > 18 yr	2.9 (1.3-6.2)
					HbA1c > 10%	2.6 (1.1-6.4)
Rahlenbeck et al[40], 1997	Ethiopia	170	T1DM and T2DM	albuminuria: > 30 mg/L	Duration of diabetes	Beta = 0.061, SE = 0.018 for T1DM	< 0.001	Hypertensive patients excluded
					Systolic blood pressure	Beta = 0.027, SE = 0.005 for T1DM	< 0.001
Wanjohi et al[45], 2002	Kenya	100	T2DM	Proteinuria ≥ 20mg	None identified
Nambuya et al[38], 1996	Uganda	252	T1DM and T2DM	Proteinuria (no detail)	None assessed
Rasmussen et al[41], 2013	Zambia	101	T1DM and T2DM	Microalbuminuria: ACR = 3.5-35.0 for women and 2.5-25.0 mg/mmol for menMacroalbuminuria were ACR> 35.0 for women and > 25.0 for men	None assessed
Bentata et al[19], 2013	Maroc	72	T1DM	End-stage renal disease: eGFR < 15 mL/min	Hemoglobin blood (per 1 g/dL decrease)	3.18 (1.47-6.87)	0.003	No precision	These are independent risk factors for ESRD in type-1 diabetes patients with diabetic nephropathy
					Diastolic blood pressure (per 1 mmHg increase)	1.15 (1.04-1.27)	0.006
Gill et al[27], 2008	Ethiopia	105	T1DM and T2DM	Nephropathy: ACR> 25.0 mg/mmol and retinopathy presentMicroalbuminuria: ACR> 2.5 and < 25.0 mg/mmol in men and > 3.5 and< 25.0 mg/mmol in women	None assessed
Bouzid et al[21], 2011	Tunisia	689	T2DM	Renal failure: creatinine clearance < 60 mL/min (Cockroft-Gault)	Older age	Not provided	< 0.00001
					Hypertension		< 0.00001
					Long duration of diabetes		< 0.001
					Higher BMI		0.02
					Dyslipidemia		0.01
Janmohamed et al[29], 2013	Tanzania	369	T1DM and T2DM	CKD: eGFR < 60 mL/min per 1.73 m2 (Cockroft-Gault) or microalbuminuria (> 20 mg/L) or overt proteinuria	Older age	1.03 (1.00-1.05)	0.03	Adjustment made, but no precision
Danquah et al[23], 2012	Ghana	671	T2DM	Proteinuria ≥ 20mg/l	Not assessed
Lutale et al[33], 2007	Tanzania	244	T1DM and T2DM	Abnormal proteinuria: AER > 20 μg/min	Duration of diabetes	0.090 (0.049- 0.131)	< 0.0001	Predictors in the model: diabetes duration, Systolic BP, age, serum creatinine	Measure of association is β
					Elevated systolic blood pressure	0.012 (0.003-0.021)	0.010
					Elevated serum creatinine	0.011 (0.002- 0.020)	0.016
Worku et al[46], 2010	Ethiopia	305	T1DM and T2DM	Proteinuria (no detail)	Duration of diabetes	Not provided	0.001
					T2DM on insulin		0.018
Makulo et al[35], 2010	DR Congo	81	No precision	Microalbuminuria: ACR 30-299 mg/gMacroalbuminuria: ACR ≥ 300 mg/gRenal failure: eGFR < 60 mL/min per 1.73 m2	Not assessed
Eghan et al[25], 2007	Ghana	109	T1DM and T2DM	Microalbuminuria: ACR 30-300 mg/g	Duration of diabetes		0.04		The associations were assessed by comparing patients with and without microalbuminuria
					Serum creatinine		0.05
					Blood urea nitrogen		0.01
					Urine potassium		0.0061
Alebiosu et al[17], 2004	Nigeria	162	T2DM	No precision	Duration of diabetes		< 0.05		The study assessed the predictors of diabetic nephropathy comparing T2DM patients with and without nephropathy
					Serum total cholesterol		< 0.05
					Alcohol > 30 mg/d		< 0.05
					Peripheral vascular disease		< 0.05
					Stroke		< 0.05

CKD: Chronic kidney disease; BMI: Body mass index; ACR: Albumin-to-Creatinine Ratio; T1DM: Type 1 diabetes mellitus; T2DM: Type 2 diabetes mellitus; eGFR: Epidermal growth factor receptor.