Table 1.

Studies detailing health risks associated with hyperglycemia in individuals with prediabetes and without diabetes.

S.No		Studies	Type of study	Glycemic variations and outcomes
				Type of glycemic variation	Decision range/cut-off	Outcomes
1.		Wang et al. (2020) [30]	Retrospective	Fasting blood glucose (FBG)	FBG ≥ 126 mg/dL	Fasting blood glucose ≥ 126 mg/dL was associated with 28-day mortality risk in COVID-19 patients
2.		Li et al. (2020) [27]	Retrospective	Blood glucose within 24 h after ICU admission	Average, minimum, and maximum blood glucose levels within 24 h of hospital admission	Predicted lowest mortality risk and better prognosis for average and maximin blood glucose in the range of 110-140 mg/dL and for minimum blood glucose in the range of 80-110mg/dL within 24 hr after ICU admission
3.		Mcgrade et al. (2019) [26]	Retrospective	Elevated blood glucose during hospital admission	Blood glucose levels in quartiles; <55 mg/dL, 55–140 mg/dL,140–200 mg/dL and >200 mg/dL	Highest mortality in quartiles with blood glucose levels <55 mg/dL and >200 mg/dL
4.		Lee et al. (2018) [15]	Retrospective	Normal fasting glucose (NFG): Impaired fasting plasma glucose (IFG)	NFG< 100 mg/dL: IFG:100.0–125.9 mg/dL	Increased all-cause mortality in patients when status is shifted from NFG to IFG.
				Impaired fasting glucose (IFG): Diabetic fasting glucose (DFG)	IFG: 100.0–125.9 mg/dL: DFG≥ 126.0 mg/dL	Increased risk of stroke and all-cause mortality in patients when status is shifted from NFG to DFG
5.		Ausk et al. (2010) [8]	Prospective	Insulin resistance by homeostasis model assessment	Quartiles of HOMA-IR HOMA-IR < 1.4 HOMA-IR >1.4–2.0 HOMA-IR>2.0–2.8 HOMA-IR>2.8	Increased mortality risk in quartile with HOMA-IR>2.8 Increased cardiovascular mortality in quartiles with HOMA-IR >1.4–2.0 HOMA-IR>2.0–2.8 HOMA-IR>2.8
6.		Barsheshet et al. (2006) [28]	Prospective	Admission blood glucose levels	Admission blood glucose: First tertile: 84–97 mg/dL Second tertile: 108–121 mg/dL Third tertile: 136–162 mg/dL	Increased in- hospital and 60-day mortality observed in third tertile with admission blood glucose levels are between is 136–162 mg/dL Each 18 mg/dL rise in blood glucose was associated with 31% in-hospital mortality risk and 12% 60-day mortality
7.	Levintan et al. (2004) [17]		Meta-analysis of prospective studies	High post-challenge blood glucose	Post-challenge blood glucose Highest postchallenge glucose midpoint range :150-194 mg/dL Lowest postchallenge glucose midpoint range : 69-107 mg/dL	Increased risk of CVD in individuals with highest post-challenge blood glucose, midpoint range:150–194 mg/dL compared to individuals with lowest postchallenge glucose midpoint range.
8.	Balkau et al. (1998) [6]		Review on Whitehall, Paris Prospective & Helsinki Policeman studies	High but non-diabetic blood glucose levels	2 h blood glucose and fasting blood glucose	Increased risk of all-cause mortality observed for subjects in upper 20% of 2 h glucose & upper 2.5% of fasting blood in comparison with subjects in the lower 80% of these distributions