Table 1.

Study demographics

DM	Study	Study type	Country	Sample	Controls	Metabolic syndrome definition	Diabetes mellitus ascertainment	KSD ascertainment	M:F (%)	Mean age
Cohort	Taylor et al 27	Prospective cohort	USA	NHS I (1980–2000: 20-year f/u)+II (1991–2001: 20-year f/u) (female nurses), HPFS participants (1986–2000: 14-year f/u) (Health Professionals Follow-up Study - all male) – ‘diabetics’, those with known KSD excluded	NHS I+II, HPFS participants - non-diabetics	N/A	Biennial health questionnaire with supplementary questionnaire on symptoms, diagnostic tests and treatment - DM diagnosis corroborated by medical record review. T1 (≥2 episodes of ketonuria/ketoacidosis) and T2 included.	Biennial health questionnaire and medical record review for corroboration - incident stone with pain/haematuria	NHS: Entirely female HPFS: Entirely male	NHS I: 48.6; NHS II: 37.6; HPFS: 60.9
	Chen et al 28	Retrospective cohort	Taiwan	National Health Insurance system database - prospectively maintained - patients with DM (T1+T2) (2000–2007: 7 years f/u). Known KSD excluded at start.	Without DM and excluding patients who developed DM in follow-up period	N/A	At least three outpatient visits for DM from 2000 to 2002 with corresponding health insurance records; ICD-9-CM 250; A-code A181. T1+T2 included	Health insurance records; ICD9-CM 592; A-code A352, excluding bladder stones. Only new stones included	50:50	N/A
	Akoudad et al 29	Prospective cohort	USA	ARIC study participants: Visit 3 (1993–1995) to 2005 with incident KSD (patient reported physician diagnosis of KSD at baseline excluded). F/U – mean 10.8 years.	Without incident KSD	N/A	Receiving diabetic medication, OGTT with FPG>110 mg/dL, FPG>126 mg/dL, patient reported physician diagnosis. Unclear T1/T2 differentiation.	ICD-9 codes: 592, 592.0, 592.1, 592.9, 274.11 on discharge summaries	42:58	60.0±5.7 (calculated)
CaCo	Lieske et al 31	Case-control	USA	Rochester, Olmsted County, Minnesota residents with electronically documented KSD - random sample of results of electronic medical record search of Mayo Clinic and Olmsted Clinic databases (original search n>7000)	Patients without electronic documentation of KSD, matched for age, sex and calendar year of stone	N/A	Electronic medical records using codes: ICD-9 codes 250, 357.2, 362.0, 366.41, 648.0 (gestational DM), 648.8, 790.2, 791.5, 962.3. No clear differentiation between T1+T2.	Electronic medical records using codes: ICD-9-CM 592, 594, 275.11 with case review	62: 38	45.0±18
	Davarci et al 32	Case-control	Turkey	Hospital outpatients with urolithiasis attending single centre between 2008–2009, T1DM excluded	Without urolithiasis	N/A	Receiving diabetic medication, OGTT with FPG>110 mg/dL, FPG>126 mg/dL. T1 excluded	USS, AXR, patient reported	47.5:52.5	49.0±10
XS	Meydan et al 30	Cross-sectional with matching	Turkey	Diabetic hospital attendees, unclear if inpatients or outpatients	Non-diabetic hospital attendees, unclear if inpatients or outpatients - matched for age	N/A	Unclear how defined. Included both T1 and T2.	History of KSD, XR/USS – if any positive confirmed with IVU	Cases: 30:70 Controls: 21:79	Cases: 57±10 Controls: 56±9
	Taylor et al 27	Cross-sectional	USA	Baseline characteristics: NHS I (1980) + II (1991) (female nurses), HFPS participants (1986) (male health professionals) - diabetics	Baseline characteristics: NHS I+II, HFPS participants - non-diabetics	N/A	Biennial health questionnaire with supplementary questionnaire on symptoms, diagnostic tests and treatment - DM diagnosis corroborated by medical record review	Biennial health questionnaire and medical record review for corroboration - kidney stone history	22:78	NHS I: 48.6; NHS II: 37.6; HFPS: 60.9
	Akoudad et al 29	Cross-sectional	USA	ARIC study participants: Visit 3 (1993–1995), patient reported physician diagnosis of KSD	Without KSD	N/A	Receiving diabetic medication, OGTT with FPG>110 mg/dL, FPG>126 mg/dL, patient reported physician diagnosis	Patient reported physician diagnosis	44:56 (calculated)	60.0±5.7 (calculated)
	Weinberg et al 33	Cross-sectional	USA	NHANES participants 2007–2010 with T2DM	Without DM	N/A	Self- reported history of DM, use of glucose-lowering medications (insulin or oral hypoglycemics), and self-reported diabetic comorbidities. T2 only.	Patient reported answer to: ‘have you ever had a kidney stone?’	N/A	N/A
MetS							IGT/DM ascertainment
XS	Rendina et al 34	Cross-sectional	Italy	Single centre inpatients between 2004–2005 - those with MetS or IGT. Exclusions: acute/chronic renal failure, abnormal renal anatomy, hyperthyroidism, hyperparathyroidism, treatment for osteoporosis, metabolic bone disorders, neoplasia	Those without MetS or IGT	American Heart Association; National Heart, Lung, and Blood Institute: three or more of: (1) Waist circumference >102 cm in men, >88 cm in women. (2) fasting serum triglycerides >1.7 mmol/L or treatment. (3) fasting serum HDL <1.03 mmol/L in men,<1.30 mmol/L in women or treatment. (4) systolic >130 mm Hg or diastolic >85 mm Hg or treatment. (5) fasting serum glucose >5.6 mmol/L or treatment	Fasting serum glucose >5.6 mmol/L or treatment	Questionnaire re: symptoms of renal colic and ultrasonography	49:51	63.8±15.8
	West et al 35	Cross-sectional	USA	NHANES III participants (1988–1994) - those with metabolic syndrome/impaired glucose tolerance	two or fewer MetS traits/no MetS traits	American Heart Association; National Heart, Lung, and Blood Institute as per Rendina et al	Fasting serum glucose >5.6 mmol/L or treatment	Self report of physician diagnosis	48:52	58.8±17.1
	Jeong et al 37	Cross-sectional	South Korea	Single centre - health promotion patients - those with IGT or MetS	Unclear - ?those without MetS or IGT	NCEP ATP III; American Heart Association; National Heart, Lung, and Blood Institute - three or more of: Systolic >130 mm Hg, diastolic >85 mm Hg, random blood glucose >110 mg/dL, random serum triglycerides >150 mg/dL, random serum HDL <40 mg/dL in men or <50 mg/dL in women, obese range waist circumference	Fasting blood glucose >110 mg/dL	Radiological records (ultrasound and CT)	60:40	50.0±10.4
	Jung et al 36	Cross-sectional	South Korea	Single Centre - patients recruited to health promotion centre to undergo metabolic + KSD screen - study group - those with impaired glucose tolerance and those with metabolic syndrome	Unclear - ?patients without impaired glucose tolerance or metabolic syndrome	NCEP ATP III - three or more of: Systolic >130 mm Hg, diastolic >85 mm Hg, random blood glucose >110 mg/dL, random serum triglycerides >150 mg/dL, random serum HDL <40 mg/dL in men o r<50 mg/dL in women, obese range waist circumference	Fasting blood glucose >110 mg/dL	Ultrasonography	55:45	44.9±11.5
	Kim et al 38	Cross-sectional	South Korea	Single centre - health promotion patients - those with IGT or MetS	Unclear - ?those without MetS or IGT	NCEP ATP III; American Heart Association; National Heart, Lung, and Blood Institute - three or more of: Systolic >130 mm Hg, diastolic >85 mm Hg, random blood glucose >110 mg/dL, random serum triglycerides >150 mg/dL, random serum HDL <40 mg/dL in men or <50 mg/dL in women	Fasting blood glucose >110 mg/dL	Ultrasonography	58:42	42.3±8.4
	Lee et al 39	Cross-sectional	Taiwan	Single centre - men undergoing free health screening - those with MetS/DM	Unclear - ?those without MetS or DM	Three of the five following criteria: patients were defined as having MetS by the presence of at least three of five of the following criteria: waist circumference (WC) 90 cm, high-density lipoprotein (HDL) cholesterol 540 mg/dL, triglyceride (TG) 150 mg/ dL, blood pressure (BP) 130/85 mm Hg or diagnosed hypertension on therapy and fasting blood glucose (FBG) 4100 mg/dL or have a diagnosis of T2DM.	T2DM - fasting BGL >126 mg/dL	(a) Characteristic clinical findings diagnosed by a physician with available medical records; (b) evidence of kidney stones from ultrasonography judged by an investigator (urologist); (c) operative history of stones removal from kidney.	100:0	55.6±4.6

CaCo = Case Control; XS = Cross-Sectional; OGTT = Oral Glucose Tolerance Test; FPG = Fasting Plasma Glucose; AXR = Abdominal X-Ray; IVU = Intravenous Urogram; NCEP ATP III = National Cholesterol Education Programme Adult Treatment Programme 3rd Iteration.

BGL, blood glucose level; DM, diabetes mellitus; f/u, follow-up; ICD-9-CM, International Classification of Diseases, Ninth Revision, Clinical Modification; IGT, impaired glucose tolerance; KSD, kidney stone disease; MetS, metabolic syndrome; N/A, not available; NHANES, National Health and Nutrition Examination Survey; NHS, National Health Service; T1, type 1 diabetes mellitus; T2, type 2 diabetes mellitus.