Table 1. Baseline characteristics of the 17 studies included.

Studies and years	Country (region)	Recruitment years	Age (year)	Follow-up	Patients with DM		NSCLC stage	Treatment method	NOS
					No./Total	No. %
Bergamino et al., 201933)	Spain	2010–2014	Median: 64 Range: 37–87	NA	56/170	32.9	IIIA–IIIB	Chemotherapy	8
Motoishi et al., 201717)	Japan	2007–2015	Mean: 79.5	NA	27/124	17.8	IA–IIIB	Surgery	8
Humar et al., 201721)	Slovenia	2005–2010	NA	Median: 9.79 m	18/167	10.8	IIIB–IV	Chemotherapy	6
Hershman et al., 201628)	USA	1991–2011	NA	NA	48/222	21.6	IIIB–IV	NA	8
Medaiors et al., 201629)	USA	2004–2013	NA	Median: 19.5 m	81/158	51.2	IA–IIB	Surgery	8
Imai et al., 201518)	Japan	2002–2009	Median: 64 Range: 40–75	NA	30–159	18.8	IIIA–IIIB	Radiotherapy Chemotherapy	8
Ahmed et al., 201523)	USA	1999–2013	Median: 65	Median: 17 m	20/146	13.7	IA–IV	Chemoradiation Therapy	4
Jeon et al., 201519)	Korea	2004–2010	Median: 64 Range: 32–81	Median: 40 m	42/271	15.5	I–II	Surgery	7
Inal et al., 201430)	Turkey	2001–2012	Median: DM: 60 Non-DM: 58	NA	66/442	14.9	III–IV	Chemotherapy	6
Inachina et al., 2014	Denmark	2007–2015	NA	NA	233/10378	2.2	NA	Surgery or nonsurgical treatment	6
Dhillon et al., 201424)	USA	2002–2011	Mean: 68.5 Range: 21–93	NA	71/409	17.4	IA–IB	Surgery	4
Luo et al., 201220)	Taiwan	2005–2007	Mean: 67.8	Median: 10.5 m	119/229	52.0	IA–IV	Surgery or nonsurgical treatment	8
Washington et al., 201225)	USA	1995–2005	Median: 67m Range: 21–92	Median: 30 m	122/957	12.7	IA–IIA	Surgery	8
Bartling et al., 201127)	German	1998–2003	Mean: 66.7	Maximum: 60 m	55/166	33.1	IA–VI	Surgery	8
Hatlen et al., 201126)	Norway	2005–2006	Mean: 64.4	NA	17/436	3.9	IIIB–IV	Chemotherapy	6
Win et al., 200831)	UK	? –2006	Mean: 69 Range: 42–85	Range: 3–5y	12/120	10	IA–IIIB	Surgery	5
Van de Poll-France et al., 200732)	Netherlands	1995–2002	Mean: 65.7	Maximum: 60 m	581/6690	8.7	IA–VI	Surgery or nonsurgical treatment	9

DM: diabetes mellitus; m: month; NA: not applicable; NOS: Newcastle Ottawa scale; NSCLC: non-small-cell lung cancer; y: year